Undo: split text undo steps out of the data-block

This moves undo storage into a separate struct which is passed
in from the undo system.

11 files changed, 384 insertions, 360 deletions

diff --git a/source/blender/blenkernel/BKE_text.h b/source/blender/blenkernel/BKE_text.h
index b3b1ad23b32..98db06752c8 100644
--- a/source/blender/blenkernel/BKE_text.h
+++ b/source/blender/blenkernel/BKE_text.h
@@ -40,6 +40,7 @@ extern "C" {
 struct Main;
 struct Text;
 struct TextLine;
+struct TextUndoBuf;
 
 void			BKE_text_free_lines	(struct Text *text);
 void			BKE_text_free		(struct Text *text);
@@ -55,8 +56,8 @@ struct Text    *BKE_text_load	(struct Main *bmain, const char *file, const char
 void            BKE_text_copy_data(struct Main *bmain, struct Text *ta_dst, const struct Text *ta_src, const int flag);
 struct Text    *BKE_text_copy		(struct Main *bmain, const struct Text *ta);
 void            BKE_text_make_local (struct Main *bmain, struct Text *text, const bool lib_local);
-void			BKE_text_clear      (struct Text *text);
-void			BKE_text_write      (struct Text *text, const char *str);
+void			BKE_text_clear      (struct Text *text, struct TextUndoBuf *utxt);
+void			BKE_text_write      (struct Text *text, struct TextUndoBuf *utxt, const char *str);
 int             BKE_text_file_modified_check(struct Text *text);
 void            BKE_text_file_modified_ignore(struct Text *text);
 
@@ -83,29 +84,29 @@ void	txt_move_eol		(struct Text *text, const bool sel);
 void	txt_move_toline		(struct Text *text, unsigned int line, const bool sel);
 void	txt_move_to			(struct Text *text, unsigned int line, unsigned int ch, const bool sel);
 void	txt_pop_sel			(struct Text *text);
-void	txt_delete_char		(struct Text *text);
-void	txt_delete_word		(struct Text *text);
-void	txt_delete_selected	(struct Text *text);
+void	txt_delete_char		(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_delete_word		(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_delete_selected	(struct Text *text, struct TextUndoBuf *utxt);
 void	txt_sel_all			(struct Text *text);
 void	txt_sel_clear		(struct Text *text);
 void	txt_sel_line		(struct Text *text);
 char   *txt_sel_to_buf		(struct Text *text);
-void	txt_insert_buf		(struct Text *text, const char *in_buffer);
-void	txt_undo_add_op		(struct Text *text, int op);
-void	txt_do_undo			(struct Text *text);
-void	txt_do_redo			(struct Text *text);
-void	txt_split_curline	(struct Text *text);
-void	txt_backspace_char	(struct Text *text);
-void	txt_backspace_word	(struct Text *text);
-bool	txt_add_char		(struct Text *text, unsigned int add);
-bool	txt_add_raw_char	(struct Text *text, unsigned int add);
-bool	txt_replace_char	(struct Text *text, unsigned int add);
-void	txt_unindent		(struct Text *text);
-void 	txt_comment			(struct Text *text);
-void 	txt_indent			(struct Text *text);
-void	txt_uncomment		(struct Text *text);
-void	txt_move_lines		(struct Text *text, const int direction);
-void	txt_duplicate_line	(struct Text *text);
+void	txt_insert_buf		(struct Text *text, struct TextUndoBuf *utxt, const char *in_buffer);
+void	txt_undo_add_op		(struct Text *text, struct TextUndoBuf *utxt, int op);
+void	txt_do_undo			(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_do_redo			(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_split_curline	(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_backspace_char	(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_backspace_word	(struct Text *text, struct TextUndoBuf *utxt);
+bool	txt_add_char		(struct Text *text, struct TextUndoBuf *utxt, unsigned int add);
+bool	txt_add_raw_char	(struct Text *text, struct TextUndoBuf *utxt, unsigned int add);
+bool	txt_replace_char	(struct Text *text, struct TextUndoBuf *utxt, unsigned int add);
+void	txt_unindent		(struct Text *text, struct TextUndoBuf *utxt);
+void 	txt_comment		(struct Text *text, struct TextUndoBuf *utxt);
+void 	txt_indent			(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_uncomment		(struct Text *text, struct TextUndoBuf *utxt);
+void	txt_move_lines		(struct Text *text, struct TextUndoBuf *utxt, const int direction);
+void	txt_duplicate_line	(struct Text *text, struct TextUndoBuf *utxt);
 int		txt_setcurr_tab_spaces(struct Text *text, int space);
 bool	txt_cursor_is_line_start(struct Text *text);
 bool	txt_cursor_is_line_end(struct Text *text);
@@ -135,6 +136,11 @@ enum {
 	TXT_MOVE_LINE_DOWN =  1
 };
 
+typedef struct TextUndoBuf {
+	char *buf;
+	int pos, len;
+} TextUndoBuf;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/blender/blenkernel/intern/text.c b/source/blender/blenkernel/intern/text.c
index b8307031920..c7588a4ed48 100644
--- a/source/blender/blenkernel/intern/text.c
+++ b/source/blender/blenkernel/intern/text.c
@@ -168,9 +168,9 @@ enum {
 
 static void txt_pop_first(Text *text);
 static void txt_pop_last(Text *text);
-static void txt_undo_add_blockop(Text *text, int op, const char *buf);
+static void txt_undo_add_blockop(Text *text, TextUndoBuf *utxt, int op, const char *buf);
 static void txt_delete_line(Text *text, TextLine *line);
-static void txt_delete_sel(Text *text);
+static void txt_delete_sel(Text *text, TextUndoBuf *utxt);
 static void txt_make_dirty(Text *text);
 
 /***/
@@ -188,13 +188,6 @@ int txt_get_undostate(void)
 	return undoing;
 }
 
-static void init_undo_text(Text *text)
-{
-	text->undo_pos = -1;
-	text->undo_len = 0;
-	text->undo_buf = NULL;
-}
-
 /**
  * \note caller must handle `undo_buf` and `compiled` members.
  */
@@ -222,7 +215,6 @@ void BKE_text_free(Text *text)
 	BKE_text_free_lines(text);
 
 	MEM_SAFE_FREE(text->name);
-	MEM_SAFE_FREE(text->undo_buf);
 #ifdef WITH_PYTHON
 	BPY_text_free_code(text);
 #endif
@@ -236,8 +228,6 @@ void BKE_text_init(Text *ta)
 
 	ta->name = NULL;
 
-	init_undo_text(ta);
-
 	ta->nlines = 1;
 	ta->flags = TXT_ISDIRTY | TXT_ISMEM;
 	if ((U.flag & USER_TXT_TABSTOSPACES_DISABLE) == 0)
@@ -419,10 +409,6 @@ bool BKE_text_reload(Text *text)
 	txt_make_dirty(text);
 
 	/* clear undo buffer */
-	MEM_freeN(text->undo_buf);
-	init_undo_text(text);
-
-
 	if (BLI_stat(filepath_abs, &st) != -1) {
 		text->mtime = st.st_mtime;
 	}
@@ -471,8 +457,6 @@ Text *BKE_text_load_ex(Main *bmain, const char *file, const char *relpath, const
 	}
 
 	/* clear undo buffer */
-	init_undo_text(ta);
-
 	if (BLI_stat(filepath_abs, &st) != -1) {
 		ta->mtime = st.st_mtime;
 	}
@@ -526,8 +510,6 @@ void BKE_text_copy_data(Main *UNUSED(bmain), Text *ta_dst, const Text *ta_src, c
 
 	ta_dst->curl = ta_dst->sell = ta_dst->lines.first;
 	ta_dst->curc = ta_dst->selc = 0;
-
-	init_undo_text(ta_dst);
 }
 
 Text *BKE_text_copy(Main *bmain, const Text *ta)
@@ -542,25 +524,29 @@ void BKE_text_make_local(Main *bmain, Text *text, const bool lib_local)
 	BKE_id_make_local_generic(bmain, &text->id, true, lib_local);
 }
 
-void BKE_text_clear(Text *text) /* called directly from rna */
+void BKE_text_clear(Text *text, TextUndoBuf *utxt) /* called directly from rna */
 {
 	int oldstate;
 
-	oldstate = txt_get_undostate();
-	txt_set_undostate(1);
+	if (utxt) {
+		oldstate = txt_get_undostate();
+	}
+	txt_set_undostate(utxt != NULL);
+
 	txt_sel_all(text);
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
+
 	txt_set_undostate(oldstate);
 
 	txt_make_dirty(text);
 }
 
-void BKE_text_write(Text *text, const char *str) /* called directly from rna */
+void BKE_text_write(Text *text, TextUndoBuf *utxt, const char *str) /* called directly from rna */
 {
 	int oldstate;
 
 	oldstate = txt_get_undostate();
-	txt_insert_buf(text, str);
+	txt_insert_buf(text, utxt, str);
 	txt_move_eof(text, 0);
 	txt_set_undostate(oldstate);
 
@@ -1153,7 +1139,7 @@ bool txt_has_sel(Text *text)
 	return ((text->curl != text->sell) || (text->curc != text->selc));
 }
 
-static void txt_delete_sel(Text *text)
+static void txt_delete_sel(Text *text, TextUndoBuf *utxt)
 {
 	TextLine *tmpl;
 	char *buf;
@@ -1167,7 +1153,7 @@ static void txt_delete_sel(Text *text)
 
 	if (!undoing) {
 		buf = txt_sel_to_buf(text);
-		txt_undo_add_blockop(text, UNDO_DBLOCK, buf);
+		txt_undo_add_blockop(text, utxt, UNDO_DBLOCK, buf);
 		MEM_freeN(buf);
 	}
 
@@ -1408,7 +1394,7 @@ char *txt_sel_to_buf(Text *text)
 	return buf;
 }
 
-void txt_insert_buf(Text *text, const char *in_buffer)
+void txt_insert_buf(Text *text, TextUndoBuf *utxt, const char *in_buffer)
 {
 	int l = 0, u, len;
 	size_t i = 0, j;
@@ -1417,22 +1403,22 @@ void txt_insert_buf(Text *text, const char *in_buffer)
 
 	if (!in_buffer) return;
 
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 	
 	len = strlen(in_buffer);
 	buffer = BLI_strdupn(in_buffer, len);
 	len += txt_extended_ascii_as_utf8(&buffer);
 	
-	if (!undoing) txt_undo_add_blockop(text, UNDO_IBLOCK, buffer);
+	if (!undoing) txt_undo_add_blockop(text, utxt, UNDO_IBLOCK, buffer);
 
 	u = undoing;
 	undoing = 1;
 
 	/* Read the first line (or as close as possible */
 	while (buffer[i] && buffer[i] != '\n')
-		txt_add_raw_char(text, BLI_str_utf8_as_unicode_step(buffer, &i));
+		txt_add_raw_char(text, utxt, BLI_str_utf8_as_unicode_step(buffer, &i));
 	
-	if (buffer[i] == '\n') txt_split_curline(text);
+	if (buffer[i] == '\n') txt_split_curline(text, utxt);
 	else { undoing = u; MEM_freeN(buffer); return; }
 	i++;
 
@@ -1450,7 +1436,7 @@ void txt_insert_buf(Text *text, const char *in_buffer)
 		}
 		else {
 			for (j = i - l; j < i && j < len; )
-				txt_add_raw_char(text, BLI_str_utf8_as_unicode_step(buffer, &j));
+				txt_add_raw_char(text, utxt, BLI_str_utf8_as_unicode_step(buffer, &j));
 			break;
 		}
 	}
@@ -1464,7 +1450,7 @@ void txt_insert_buf(Text *text, const char *in_buffer)
 /* Undo functions */
 /******************/
 
-static bool max_undo_test(Text *text, int x)
+static bool max_undo_test(TextUndoBuf *utxt, int x)
 {
 	/* Normally over-allocating is preferred,
 	 * however in this case the buffer is small enough and re-allocation
@@ -1474,25 +1460,24 @@ static bool max_undo_test(Text *text, int x)
 	 */
 
 	/* Add one for the null terminator. */
-	text->undo_len = text->undo_pos + x + 1;
-	if (text->undo_len > TXT_MAX_UNDO) {
+	utxt->len = utxt->pos + x + 1;
+	if (utxt->len > TXT_MAX_UNDO) {
 		/* XXX error("Undo limit reached, buffer cleared\n"); */
-		MEM_freeN(text->undo_buf);
-		init_undo_text(text);
+		MEM_freeN(utxt->buf);
 		return false;
 	}
 	else {
 		/* Small reallocations on each undo step is fine. */
-		text->undo_buf = MEM_recallocN(text->undo_buf, text->undo_len);
+		utxt->buf = MEM_recallocN(utxt->buf, utxt->len);
 	}
 	return true;
 }
 
-static void txt_undo_end(Text *text)
+static void txt_undo_end(Text *UNUSED(text), TextUndoBuf *utxt)
 {
-	int undo_pos_end = text->undo_pos + 1;
-	BLI_assert(undo_pos_end + 1 == text->undo_len);
-	text->undo_buf[undo_pos_end] = '\0';
+	int undo_pos_end = utxt->pos + 1;
+	BLI_assert(undo_pos_end + 1 == utxt->len);
+	utxt->buf[undo_pos_end] = '\0';
 }
 
 /* Call once undo is done. */
@@ -1501,11 +1486,11 @@ static void txt_undo_end(Text *text)
 #endif
 
 #if 0  /* UNUSED */
-static void dump_buffer(Text *text) 
+static void dump_buffer(TextUndoBuf *utxt)
 {
 	int i = 0;
-	
-	while (i++ < text->undo_pos) printf("%d: %d %c\n", i, text->undo_buf[i], text->undo_buf[i]);
+
+	while (i++ < utxt->undo_pos) printf("%d: %d %c\n", i, utxt->buf[i], utxt->buf[i]);
 }
 
 /* Note: this function is outdated and must be updated if needed for future use */
@@ -1520,10 +1505,10 @@ void txt_print_undo(Text *text)
 	
 	printf("---< Undo Buffer >---\n");
 	
-	printf("UndoPosition is %d\n", text->undo_pos);
+	printf("UndoPosition is %d\n", utxt->pos);
 	
-	while (i <= text->undo_pos) {
-		op = text->undo_buf[i];
+	while (i <= utxt->pos) {
+		op = utxt->buf[i];
 		
 		if (op == UNDO_INSERT_1) {
 			ops = "Insert ascii ";
@@ -1589,15 +1574,15 @@ void txt_print_undo(Text *text)
 			printf(" - Char is ");
 			switch (op) {
 				case UNDO_INSERT_1: case UNDO_BS_1: case UNDO_DEL_1:
-					printf("%c", text->undo_buf[i]);
+					printf("%c", utxt->buf[i]);
 					i++;
 					break;
 				case UNDO_INSERT_2: case UNDO_BS_2: case UNDO_DEL_2:
-					printf("%c%c", text->undo_buf[i], text->undo_buf[i + 1]);
+					printf("%c%c", utxt->buf[i], utxt->buf[i + 1]);
 					i += 2;
 					break;
 				case UNDO_INSERT_3: case UNDO_BS_3: case UNDO_DEL_3:
-					printf("%c%c%c", text->undo_buf[i], text->undo_buf[i + 1], text->undo_buf[i + 2]);
+					printf("%c%c%c", utxt->buf[i], utxt->buf[i + 1], utxt->buf[i + 2]);
 					i += 3;
 					break;
 				case UNDO_INSERT_4: case UNDO_BS_4: case UNDO_DEL_4:
@@ -1605,10 +1590,10 @@ void txt_print_undo(Text *text)
 					unsigned int uc;
 					char c[BLI_UTF8_MAX + 1];
 					size_t c_len;
-					uc = text->undo_buf[i]; i++;
-					uc = uc + (text->undo_buf[i] << 8); i++;
-					uc = uc + (text->undo_buf[i] << 16); i++;
-					uc = uc + (text->undo_buf[i] << 24); i++;
+					uc = utxt->buf[i]; i++;
+					uc = uc + (utxt->buf[i] << 8); i++;
+					uc = uc + (utxt->buf[i] << 16); i++;
+					uc = uc + (utxt->buf[i] << 24); i++;
 					c_len = BLI_str_utf8_from_unicode(uc, c);
 					c[c_len] = '\0';
 					puts(c);
@@ -1619,44 +1604,44 @@ void txt_print_undo(Text *text)
 		else if (op == UNDO_DBLOCK || op == UNDO_IBLOCK) {
 			i++;
 
-			linep = text->undo_buf[i]; i++;
-			linep = linep + (text->undo_buf[i] << 8); i++;
-			linep = linep + (text->undo_buf[i] << 16); i++;
-			linep = linep + (text->undo_buf[i] << 24); i++;
+			linep = utxt->buf[i]; i++;
+			linep = linep + (utxt->buf[i] << 8); i++;
+			linep = linep + (utxt->buf[i] << 16); i++;
+			linep = linep + (utxt->buf[i] << 24); i++;
 			
 			printf(" (length %d) <", linep);
 			
 			while (linep > 0) {
-				putchar(text->undo_buf[i]);
+				putchar(utxt->buf[i]);
 				linep--; i++;
 			}
 			
-			linep = text->undo_buf[i]; i++;
-			linep = linep + (text->undo_buf[i] << 8); i++;
-			linep = linep + (text->undo_buf[i] << 16); i++;
-			linep = linep + (text->undo_buf[i] << 24); i++;
+			linep = utxt->buf[i]; i++;
+			linep = linep + (utxt->buf[i] << 8); i++;
+			linep = linep + (utxt->buf[i] << 16); i++;
+			linep = linep + (utxt->buf[i] << 24); i++;
 			printf("> (%d)", linep);
 		}
 		else if (op == UNDO_INDENT || op == UNDO_UNINDENT) {
 			i++;
 
-			charp = text->undo_buf[i]; i++;
-			charp = charp + (text->undo_buf[i] << 8); i++;
+			charp = utxt->buf[i]; i++;
+			charp = charp + (utxt->buf[i] << 8); i++;
 
-			linep = text->undo_buf[i]; i++;
-			linep = linep + (text->undo_buf[i] << 8); i++;
-			linep = linep + (text->undo_buf[i] << 16); i++;
-			linep = linep + (text->undo_buf[i] << 24); i++;
+			linep = utxt->buf[i]; i++;
+			linep = linep + (utxt->buf[i] << 8); i++;
+			linep = linep + (utxt->buf[i] << 16); i++;
+			linep = linep + (utxt->buf[i] << 24); i++;
 			
 			printf("to <%d, %d> ", linep, charp);
 
-			charp = text->undo_buf[i]; i++;
-			charp = charp + (text->undo_buf[i] << 8); i++;
+			charp = utxt->buf[i]; i++;
+			charp = charp + (utxt->buf[i] << 8); i++;
 
-			linep = text->undo_buf[i]; i++;
-			linep = linep + (text->undo_buf[i] << 8); i++;
-			linep = linep + (text->undo_buf[i] << 16); i++;
-			linep = linep + (text->undo_buf[i] << 24); i++;
+			linep = utxt->buf[i]; i++;
+			linep = linep + (utxt->buf[i] << 8); i++;
+			linep = linep + (utxt->buf[i] << 16); i++;
+			linep = linep + (utxt->buf[i] << 24); i++;
 			
 			printf("from <%d, %d>", linep, charp);
 		}
@@ -1688,113 +1673,113 @@ static void txt_undo_store_uint32(char *undo_buf, int *undo_pos, unsigned int va
 }
 
 /* store the cur cursor to the undo buffer (6 bytes)*/
-static void txt_undo_store_cur(Text *text)
+static void txt_undo_store_cur(Text *text, TextUndoBuf *utxt)
 {
-	txt_undo_store_uint16(text->undo_buf, &text->undo_pos, text->curc);
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, txt_get_span(text->lines.first, text->curl));
+	txt_undo_store_uint16(utxt->buf, &utxt->pos, text->curc);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, txt_get_span(text->lines.first, text->curl));
 }
 
 /* store the sel cursor to the undo buffer (6 bytes) */
-static void txt_undo_store_sel(Text *text)
+static void txt_undo_store_sel(Text *text, TextUndoBuf *utxt)
 {
-	txt_undo_store_uint16(text->undo_buf, &text->undo_pos, text->selc);
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, txt_get_span(text->lines.first, text->sell));
+	txt_undo_store_uint16(utxt->buf, &utxt->pos, text->selc);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, txt_get_span(text->lines.first, text->sell));
 }
 
 /* store both cursors to the undo buffer (12 bytes) */
-static void txt_undo_store_cursors(Text *text)
+static void txt_undo_store_cursors(Text *text, TextUndoBuf *utxt)
 {
-	txt_undo_store_cur(text);
-	txt_undo_store_sel(text);
+	txt_undo_store_cur(text, utxt);
+	txt_undo_store_sel(text, utxt);
 }
 
 /* store an operator along with a block of data */
-static void txt_undo_add_blockop(Text *text, int op, const char *buf)
+static void txt_undo_add_blockop(Text *text, TextUndoBuf *utxt, int op, const char *buf)
 {
 	unsigned int length = strlen(buf);
 
-	if (!max_undo_test(text, 2 + 12 + 4 + length + 4 + 1)) {
+	if (!max_undo_test(utxt, 2 + 12 + 4 + length + 4 + 1)) {
 		return;
 	}
 	/* 2 bytes */
-	text->undo_pos++;
-	text->undo_buf[text->undo_pos] = op;
-	text->undo_pos++;
+	utxt->pos++;
+	utxt->buf[utxt->pos] = op;
+	utxt->pos++;
 	/* 12 bytes */
-	txt_undo_store_cursors(text);
+	txt_undo_store_cursors(text, utxt);
 	/* 4 bytes */
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, length);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, length);
 	/* 'length' bytes */
-	strncpy(text->undo_buf + text->undo_pos, buf, length);
-	text->undo_pos += length;
+	strncpy(utxt->buf + utxt->pos, buf, length);
+	utxt->pos += length;
 	/* 4 bytes */
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, length);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, length);
 	/* 1 byte */
-	text->undo_buf[text->undo_pos] = op;
+	utxt->buf[utxt->pos] = op;
 
-	txt_undo_end(text);
+	txt_undo_end(text, utxt);
 }
 
 /* store a regular operator */
-void txt_undo_add_op(Text *text, int op)
+void txt_undo_add_op(Text *text, TextUndoBuf *utxt, int op)
 {
-	if (!max_undo_test(text, 2 + 12 + 1)) {
+	if (!max_undo_test(utxt, 2 + 12 + 1)) {
 		return;
 	}
 
 	/* 2 bytes */
-	text->undo_pos++;
-	text->undo_buf[text->undo_pos] = op;
-	text->undo_pos++;
+	utxt->pos++;
+	utxt->buf[utxt->pos] = op;
+	utxt->pos++;
 	/* 12 bytes */
-	txt_undo_store_cursors(text);
+	txt_undo_store_cursors(text, utxt);
 	/* 1 byte */
-	text->undo_buf[text->undo_pos] = op;
+	utxt->buf[utxt->pos] = op;
 
-	txt_undo_end(text);
+	txt_undo_end(text, utxt);
 }
 
 /* store an operator for a single character */
-static void txt_undo_add_charop(Text *text, int op_start, unsigned int c)
+static void txt_undo_add_charop(Text *text, TextUndoBuf *utxt, int op_start, unsigned int c)
 {
 	char utf8[BLI_UTF8_MAX];
 	size_t i, utf8_size = BLI_str_utf8_from_unicode(c, utf8);
 	
 	if (utf8_size < 4 && 0) {
-		if (!max_undo_test(text, 2 + 6 + utf8_size + 1)) {
+		if (!max_undo_test(utxt, 2 + 6 + utf8_size + 1)) {
 			return;
 		}
 		/* 2 bytes */
-		text->undo_pos++;
-		text->undo_buf[text->undo_pos] = op_start + utf8_size - 1;
-		text->undo_pos++;
+		utxt->pos++;
+		utxt->buf[utxt->pos] = op_start + utf8_size - 1;
+		utxt->pos++;
 		/* 6 bytes */
-		txt_undo_store_cur(text);
+		txt_undo_store_cur(text, utxt);
 		/* 'utf8_size' bytes */
 		for (i = 0; i < utf8_size; i++) {
-			text->undo_buf[text->undo_pos] = utf8[i];
-			text->undo_pos++;
+			utxt->buf[utxt->pos] = utf8[i];
+			utxt->pos++;
 		}
 		/* 1 byte */
-		text->undo_buf[text->undo_pos] = op_start + utf8_size - 1;
+		utxt->buf[utxt->pos] = op_start + utf8_size - 1;
 	}
 	else {
-		if (!max_undo_test(text, 2 + 6 + 4 + 1)) {
+		if (!max_undo_test(utxt, 2 + 6 + 4 + 1)) {
 			return;
 		}
 		/* 2 bytes */
-		text->undo_pos++;
-		text->undo_buf[text->undo_pos] = op_start + 3;
-		text->undo_pos++;
+		utxt->pos++;
+		utxt->buf[utxt->pos] = op_start + 3;
+		utxt->pos++;
 		/* 6 bytes */
-		txt_undo_store_cur(text);
+		txt_undo_store_cur(text, utxt);
 		/* 4 bytes */
-		txt_undo_store_uint32(text->undo_buf, &text->undo_pos, c);
+		txt_undo_store_uint32(utxt->buf, &utxt->pos, c);
 		/* 1 byte */
-		text->undo_buf[text->undo_pos] = op_start + 3;
+		utxt->buf[utxt->pos] = op_start + 3;
 	}
 	
-	txt_undo_end(text);
+	txt_undo_end(text, utxt);
 }
 
 /* extends Link */
@@ -1808,7 +1793,7 @@ struct LinkInt {
  * of the lines that should not be indented back.
  */
 static void txt_undo_add_unprefix_op(
-        Text *text, char undo_op,
+        Text *text, TextUndoBuf *utxt, char undo_op,
         const ListBase *line_index_mask, const int line_index_mask_len)
 {
 	struct LinkInt *idata;
@@ -1816,35 +1801,35 @@ static void txt_undo_add_unprefix_op(
 	BLI_assert(BLI_listbase_count(line_index_mask) == line_index_mask_len);
 
 	/* OP byte + UInt32 count + counted UInt32 line numbers + UInt32 count + 12-bytes selection + OP byte */
-	if (!max_undo_test(text, 2 + 4 + (line_index_mask_len * 4) + 4 + 12 + 1)) {
+	if (!max_undo_test(utxt, 2 + 4 + (line_index_mask_len * 4) + 4 + 12 + 1)) {
 		return;
 	}
 
 	/* 2 bytes */
-	text->undo_pos++;
-	text->undo_buf[text->undo_pos] = undo_op;
-	text->undo_pos++;
+	utxt->pos++;
+	utxt->buf[utxt->pos] = undo_op;
+	utxt->pos++;
 	/* Adding number of line numbers to read
 	 * 4 bytes */
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, line_index_mask_len);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, line_index_mask_len);
 
 	/* Adding linenumbers of lines that shall not be indented if undoing.
 	 * 'line_index_mask_len * 4' bytes */
 	for (idata = line_index_mask->first; idata; idata = idata->next) {
-		txt_undo_store_uint32(text->undo_buf, &text->undo_pos, idata->value);
+		txt_undo_store_uint32(utxt->buf, &utxt->pos, idata->value);
 	}
 
 	/* Adding number of line numbers to read again.
 	 * 4 bytes */
-	txt_undo_store_uint32(text->undo_buf, &text->undo_pos, line_index_mask_len);
+	txt_undo_store_uint32(utxt->buf, &utxt->pos, line_index_mask_len);
 	/* Adding current selection.
 	 * 12 bytes */
-	txt_undo_store_cursors(text);
+	txt_undo_store_cursors(text, utxt);
 	/* Closing with OP (same as above).
 	 * 1 byte */
-	text->undo_buf[text->undo_pos] = undo_op;
+	utxt->buf[utxt->pos] = undo_op;
 	/* Marking as last undo operation */
-	txt_undo_end(text);
+	txt_undo_end(text, utxt);
 }
 
 static unsigned short txt_undo_read_uint16(const char *undo_buf, int *undo_pos)
@@ -1999,9 +1984,9 @@ static unsigned int txt_redo_read_unicode(const char *undo_buf, int *undo_pos, s
 	return unicode;
 }
 
-void txt_do_undo(Text *text)
+void txt_do_undo(Text *text, TextUndoBuf *utxt)
 {
-	int op = text->undo_buf[text->undo_pos];
+	int op = utxt->buf[utxt->pos];
 	int prev_flags;
 	unsigned int linep;
 	unsigned int uni_char;
@@ -2010,11 +1995,11 @@ void txt_do_undo(Text *text)
 	unsigned short charp;
 	char *buf;
 	
-	if (text->undo_pos < 0) {
+	if (utxt->pos < 0) {
 		return;
 	}
 
-	text->undo_pos--;
+	utxt->pos--;
 
 	undoing = 1;
 	
@@ -2023,16 +2008,16 @@ void txt_do_undo(Text *text)
 		case UNDO_INSERT_2:
 		case UNDO_INSERT_3:
 		case UNDO_INSERT_4:
-			text->undo_pos -= op - UNDO_INSERT_1 + 1;
+			utxt->pos -= op - UNDO_INSERT_1 + 1;
 			
 			/* get and restore the cursors */
-			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_undo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 			
-			txt_delete_char(text);
+			txt_delete_char(text, utxt);
 			
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 
 		case UNDO_BS_1:
@@ -2040,16 +2025,16 @@ void txt_do_undo(Text *text)
 		case UNDO_BS_3:
 		case UNDO_BS_4:
 			charp = op - UNDO_BS_1 + 1;
-			uni_char = txt_undo_read_unicode(text->undo_buf, &text->undo_pos, charp);
+			uni_char = txt_undo_read_unicode(utxt->buf, &utxt->pos, charp);
 			
 			/* get and restore the cursors */
-			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_undo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 			
-			txt_add_char(text, uni_char);
+			txt_add_char(text, utxt, uni_char);
 
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 
 		case UNDO_DEL_1:
@@ -2057,50 +2042,50 @@ void txt_do_undo(Text *text)
 		case UNDO_DEL_3:
 		case UNDO_DEL_4:
 			charp = op - UNDO_DEL_1 + 1;
-			uni_char = txt_undo_read_unicode(text->undo_buf, &text->undo_pos, charp);
+			uni_char = txt_undo_read_unicode(utxt->buf, &utxt->pos, charp);
 
 			/* get and restore the cursors */
-			txt_undo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_undo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 
-			txt_add_char(text, uni_char);
+			txt_add_char(text, utxt, uni_char);
 
 			txt_move_left(text, 0);
 
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 
 		case UNDO_DBLOCK:
 		{
 			int i;
 			/* length of the string in the buffer */
-			linep = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
+			linep = txt_undo_read_uint32(utxt->buf, &utxt->pos);
 
 			buf = MEM_mallocN(linep + 1, "dblock buffer");
 			for (i = 0; i < linep; i++) {
-				buf[(linep - 1) - i] = text->undo_buf[text->undo_pos];
-				text->undo_pos--;
+				buf[(linep - 1) - i] = utxt->buf[utxt->pos];
+				utxt->pos--;
 			}
 			buf[i] = 0;
 
 			/* skip over the length that was stored again */
-			text->undo_pos -= 4;
+			utxt->pos -= 4;
 
 			/* Get the cursor positions */
-			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_undo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 
 			/* move cur to location that needs buff inserted */
 			txt_move_to(text, curln, curc, 0);
 			
-			txt_insert_buf(text, buf);
+			txt_insert_buf(text, utxt, buf);
 			MEM_freeN(buf);
 
 			/* restore the cursors */
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 
-			text->undo_pos--;
+			utxt->pos--;
 			
 			break;
 		}
@@ -2108,23 +2093,23 @@ void txt_do_undo(Text *text)
 		{
 			int i;
 			/* length of the string in the buffer */
-			linep = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
+			linep = txt_undo_read_uint32(utxt->buf, &utxt->pos);
 			
 			/* txt_backspace_char removes utf8-characters, not bytes */
 			buf = MEM_mallocN(linep + 1, "iblock buffer");
 			for (i = 0; i < linep; i++) {
-				buf[(linep - 1) - i] = text->undo_buf[text->undo_pos];
-				text->undo_pos--;
+				buf[(linep - 1) - i] = utxt->buf[utxt->pos];
+				utxt->pos--;
 			}
 			buf[i] = 0;
 			linep = BLI_strlen_utf8(buf);
 			MEM_freeN(buf);
 			
 			/* skip over the length that was stored again */
-			text->undo_pos -= 4;
+			utxt->pos -= 4;
 
 			/* get and restore the cursors */
-			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_undo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
@@ -2140,9 +2125,9 @@ void txt_do_undo(Text *text)
 				text->flags = prev_flags;
 			}
 			
-			txt_delete_selected(text);
+			txt_delete_selected(text, utxt);
 			
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 		}
 		case UNDO_INDENT:
@@ -2151,37 +2136,37 @@ void txt_do_undo(Text *text)
 		case UNDO_MOVE_LINES_UP:
 		case UNDO_MOVE_LINES_DOWN:
 			/* get and restore the cursors */
-			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_undo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 			
 			if (op == UNDO_INDENT) {
-				txt_unindent(text);
+				txt_unindent(text, utxt);
 			}
 			else if (op == UNDO_COMMENT) {
-				txt_uncomment(text);
+				txt_uncomment(text, utxt);
 			}
 			else if (op == UNDO_DUPLICATE) {
 				txt_delete_line(text, text->curl->next);
 			}
 			else if (op == UNDO_MOVE_LINES_UP) {
-				txt_move_lines(text, TXT_MOVE_LINE_DOWN);
+				txt_move_lines(text, utxt, TXT_MOVE_LINE_DOWN);
 			}
 			else if (op == UNDO_MOVE_LINES_DOWN) {
-				txt_move_lines(text, TXT_MOVE_LINE_UP);
+				txt_move_lines(text, utxt, TXT_MOVE_LINE_UP);
 			}
 			
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 		case UNDO_UNINDENT:
 		case UNDO_UNCOMMENT:
 		{
-			void (*txt_prefix_fn)(Text *);
-			void (*txt_unprefix_fn)(Text *);
+			void (*txt_prefix_fn)(Text *, TextUndoBuf *);
+			void (*txt_unprefix_fn)(Text *, TextUndoBuf *);
 			int count;
 			int i;
 			/* Get and restore the cursors */
-			txt_undo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_undo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 
@@ -2195,30 +2180,30 @@ void txt_do_undo(Text *text)
 				txt_unprefix_fn = txt_uncomment;
 			}
 
-			txt_prefix_fn(text);
+			txt_prefix_fn(text, utxt);
 
 			/* Get the count */
-			count = txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
+			count = txt_undo_read_uint32(utxt->buf, &utxt->pos);
 			/* Iterate! */
 			txt_pop_sel(text);
 
 			for (i = 0; i < count; i++) {
-				txt_move_to(text, txt_undo_read_uint32(text->undo_buf, &text->undo_pos), 0, 0);
+				txt_move_to(text, txt_undo_read_uint32(utxt->buf, &utxt->pos), 0, 0);
 				/* Un-un-unindent/comment */
-				txt_unprefix_fn(text);
+				txt_unprefix_fn(text, utxt);
 			}
 			/* Restore selection */
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 			/* Jumo over count */
-			txt_undo_read_uint32(text->undo_buf, &text->undo_pos);
+			txt_undo_read_uint32(utxt->buf, &utxt->pos);
 			/* Jump over closing OP byte */
-			text->undo_pos--;
+			utxt->pos--;
 			break;
 		}
 		default:
 			//XXX error("Undo buffer error - resetting");
-			text->undo_pos = -1;
+			utxt->pos = -1;
 			
 			break;
 	}
@@ -2226,7 +2211,7 @@ void txt_do_undo(Text *text)
 	undoing = 0;
 }
 
-void txt_do_redo(Text *text)
+void txt_do_redo(Text *text, TextUndoBuf *utxt)
 {
 	char op;
 	char *buf;
@@ -2236,11 +2221,11 @@ void txt_do_redo(Text *text)
 	unsigned int curln, selln;
 	unsigned short curc, selc;
 	
-	text->undo_pos++;
-	op = text->undo_buf[text->undo_pos];
+	utxt->pos++;
+	op = utxt->buf[utxt->pos];
 	
 	if (!op) {
-		text->undo_pos--;
+		utxt->pos--;
 		return;
 	}
 	
@@ -2251,35 +2236,35 @@ void txt_do_redo(Text *text)
 		case UNDO_INSERT_2:
 		case UNDO_INSERT_3:
 		case UNDO_INSERT_4:
-			text->undo_pos++;
+			utxt->pos++;
 			
 			/* get and restore the cursors */
-			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_redo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 			
 			charp = op - UNDO_INSERT_1 + 1;
-			uni_uchar = txt_redo_read_unicode(text->undo_buf, &text->undo_pos, charp);
+			uni_uchar = txt_redo_read_unicode(utxt->buf, &utxt->pos, charp);
 
-			txt_add_char(text, uni_uchar);
+			txt_add_char(text, utxt, uni_uchar);
 			break;
 
 		case UNDO_BS_1:
 		case UNDO_BS_2:
 		case UNDO_BS_3:
 		case UNDO_BS_4:
-			text->undo_pos++;
+			utxt->pos++;
 
 			/* get and restore the cursors */
-			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_redo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 
-			text->undo_pos += op - UNDO_BS_1 + 1;
+			utxt->pos += op - UNDO_BS_1 + 1;
 			
 			/* move right so we backspace the correct char */
 			txt_move_right(text, 0);
-			txt_backspace_char(text);
+			txt_backspace_char(text, utxt);
 
 			break;
 
@@ -2287,60 +2272,60 @@ void txt_do_redo(Text *text)
 		case UNDO_DEL_2:
 		case UNDO_DEL_3:
 		case UNDO_DEL_4:
-			text->undo_pos++;
+			utxt->pos++;
 
 			/* get and restore the cursors */
-			txt_redo_read_cur(text->undo_buf, &text->undo_pos, &curln, &curc);
+			txt_redo_read_cur(utxt->buf, &utxt->pos, &curln, &curc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 			
-			text->undo_pos += op - UNDO_DEL_1 + 1;
+			utxt->pos += op - UNDO_DEL_1 + 1;
 
-			txt_delete_char(text);
+			txt_delete_char(text, utxt);
 
 			break;
 
 		case UNDO_DBLOCK:
-			text->undo_pos++;
+			utxt->pos++;
 
 			/* get and restore the cursors */
-			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_redo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 
 			/* length of the block */
-			linep = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
+			linep = txt_redo_read_uint32(utxt->buf, &utxt->pos);
 			
-			text->undo_pos += linep;
+			utxt->pos += linep;
 
 			/* skip over the length that was stored again */
-			text->undo_pos += 4;
+			utxt->pos += 4;
 			
-			txt_delete_sel(text);
+			txt_delete_sel(text, utxt);
 
 			break;
 
 		case UNDO_IBLOCK:
-			text->undo_pos++;
+			utxt->pos++;
 
 			/* get and restore the cursors */
-			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_redo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, curln, curc, 1);
 
 			/* length of the block */
-			linep = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
+			linep = txt_redo_read_uint32(utxt->buf, &utxt->pos);
 
 			buf = MEM_mallocN(linep + 1, "iblock buffer");
-			memcpy(buf, &text->undo_buf[text->undo_pos], linep);
-			text->undo_pos += linep;
+			memcpy(buf, &utxt->buf[utxt->pos], linep);
+			utxt->pos += linep;
 			buf[linep] = 0;
 			
-			txt_insert_buf(text, buf);
+			txt_insert_buf(text, utxt, buf);
 			MEM_freeN(buf);
 
 			/* skip over the length that was stored again */
-			text->undo_pos += 4;
+			utxt->pos += 4;
 
 			break;
 			
@@ -2350,38 +2335,38 @@ void txt_do_redo(Text *text)
 		case UNDO_DUPLICATE:
 		case UNDO_MOVE_LINES_UP:
 		case UNDO_MOVE_LINES_DOWN:
-			text->undo_pos++;
+			utxt->pos++;
 
 			/* get and restore the cursors */
-			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_redo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
 
 			if (op == UNDO_INDENT) {
-				txt_indent(text);
+				txt_indent(text, utxt);
 			}
 			else if (op == UNDO_COMMENT) {
-				txt_comment(text);
+				txt_comment(text, utxt);
 			}
 			else if (op == UNDO_UNCOMMENT) {
-				txt_uncomment(text);
+				txt_uncomment(text, utxt);
 			}
 			else if (op == UNDO_DUPLICATE) {
-				txt_duplicate_line(text);
+				txt_duplicate_line(text, utxt);
 			}
 			else if (op == UNDO_MOVE_LINES_UP) {
 				/* offset the cursor by + 1 */
 				txt_move_to(text, curln + 1, curc, 0);
 				txt_move_to(text, selln + 1, selc, 1);
 
-				txt_move_lines(text, TXT_MOVE_LINE_UP);
+				txt_move_lines(text, utxt, TXT_MOVE_LINE_UP);
 			}
 			else if (op == UNDO_MOVE_LINES_DOWN) {
 				/* offset the cursor by - 1 */
 				txt_move_to(text, curln - 1, curc, 0);
 				txt_move_to(text, selln - 1, selc, 1);
 
-				txt_move_lines(text, TXT_MOVE_LINE_DOWN);
+				txt_move_lines(text, utxt, TXT_MOVE_LINE_DOWN);
 			}
 
 			/* re-restore the cursors since they got moved when redoing */
@@ -2394,24 +2379,24 @@ void txt_do_redo(Text *text)
 			int count;
 			int i;
 
-			text->undo_pos++;
+			utxt->pos++;
 			/* Scan all the stuff described in txt_undo_add_unindent_op */
-			count = txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
+			count = txt_redo_read_uint32(utxt->buf, &utxt->pos);
 			for (i = 0; i < count; i++) {
-				txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
+				txt_redo_read_uint32(utxt->buf, &utxt->pos);
 			}
 			/* Count again */
-			txt_redo_read_uint32(text->undo_buf, &text->undo_pos);
+			txt_redo_read_uint32(utxt->buf, &utxt->pos);
 			/* Get the selection and re-unindent */
-			txt_redo_read_cursors(text->undo_buf, &text->undo_pos, &curln, &curc, &selln, &selc);
+			txt_redo_read_cursors(utxt->buf, &utxt->pos, &curln, &curc, &selln, &selc);
 			txt_move_to(text, curln, curc, 0);
 			txt_move_to(text, selln, selc, 1);
-			txt_unindent(text);
+			txt_unindent(text, utxt);
 			break;
 		}
 		default:
 			//XXX error("Undo buffer error - resetting");
-			text->undo_pos = -1;
+			utxt->pos = -1;
 			
 			break;
 	}
@@ -2423,16 +2408,16 @@ void txt_do_redo(Text *text)
 /* Line editing functions */ 
 /**************************/
 
-void txt_split_curline(Text *text)
+void txt_split_curline(Text *text, TextUndoBuf *utxt)
 {
 	TextLine *ins;
 	char *left, *right;
 
 	if (!text->curl) return;
 
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 
-	if (!undoing) txt_undo_add_charop(text, UNDO_INSERT_1, '\n');
+	if (!undoing) txt_undo_add_charop(text, utxt, UNDO_INSERT_1, '\n');
 	
 	/* Make the two half strings */
 
@@ -2504,7 +2489,7 @@ static void txt_combine_lines(Text *text, TextLine *linea, TextLine *lineb)
 	txt_clean_text(text);
 }
 
-void txt_duplicate_line(Text *text)
+void txt_duplicate_line(Text *text, TextUndoBuf *utxt)
 {
 	TextLine *textline;
 	
@@ -2517,18 +2502,18 @@ void txt_duplicate_line(Text *text)
 		txt_make_dirty(text);
 		txt_clean_text(text);
 		
-		if (!undoing) txt_undo_add_op(text, UNDO_DUPLICATE);
+		if (!undoing) txt_undo_add_op(text, utxt, UNDO_DUPLICATE);
 	}
 }
 
-void txt_delete_char(Text *text) 
+void txt_delete_char(Text *text, TextUndoBuf *utxt)
 {
 	unsigned int c = '\n';
 
 	if (!text->curl) return;
 
 	if (txt_has_sel(text)) { /* deleting a selection */
-		txt_delete_sel(text);
+		txt_delete_sel(text, utxt);
 		txt_make_dirty(text);
 		return;
 	}
@@ -2554,24 +2539,24 @@ void txt_delete_char(Text *text)
 	txt_make_dirty(text);
 	txt_clean_text(text);
 	
-	if (!undoing) txt_undo_add_charop(text, UNDO_DEL_1, c);
+	if (!undoing) txt_undo_add_charop(text, utxt, UNDO_DEL_1, c);
 }
 
-void txt_delete_word(Text *text)
+void txt_delete_word(Text *text, TextUndoBuf *utxt)
 {
 	txt_jump_right(text, true, true);
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 	txt_make_dirty(text);
 }
 
-void txt_backspace_char(Text *text)
+void txt_backspace_char(Text *text, TextUndoBuf *utxt)
 {
 	unsigned int c = '\n';
 	
 	if (!text->curl) return;
 	
 	if (txt_has_sel(text)) { /* deleting a selection */
-		txt_delete_sel(text);
+		txt_delete_sel(text, utxt);
 		txt_make_dirty(text);
 		return;
 	}
@@ -2603,13 +2588,13 @@ void txt_backspace_char(Text *text)
 	txt_make_dirty(text);
 	txt_clean_text(text);
 	
-	if (!undoing) txt_undo_add_charop(text, UNDO_BS_1, c);
+	if (!undoing) txt_undo_add_charop(text, utxt, UNDO_BS_1, c);
 }
 
-void txt_backspace_word(Text *text)
+void txt_backspace_word(Text *text, TextUndoBuf *utxt)
 {
 	txt_jump_left(text, true, true);
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 	txt_make_dirty(text);
 }
 
@@ -2618,17 +2603,17 @@ void txt_backspace_word(Text *text)
  * Remember to change this string according to max tab size */
 static char tab_to_spaces[] = "    ";
 
-static void txt_convert_tab_to_spaces(Text *text)
+static void txt_convert_tab_to_spaces(Text *text, TextUndoBuf *utxt)
 {
 	/* sb aims to pad adjust the tab-width needed so that the right number of spaces
 	 * is added so that the indention of the line is the right width (i.e. aligned
 	 * to multiples of TXT_TABSIZE)
 	 */
 	const char *sb = &tab_to_spaces[text->curc % TXT_TABSIZE];
-	txt_insert_buf(text, sb);
+	txt_insert_buf(text, utxt, sb);
 }
 
-static bool txt_add_char_intern(Text *text, unsigned int add, bool replace_tabs)
+static bool txt_add_char_intern(Text *text, TextUndoBuf *utxt, unsigned int add, bool replace_tabs)
 {
 	char *tmp, ch[BLI_UTF8_MAX];
 	size_t add_len;
@@ -2636,19 +2621,19 @@ static bool txt_add_char_intern(Text *text, unsigned int add, bool replace_tabs)
 	if (!text->curl) return 0;
 
 	if (add == '\n') {
-		txt_split_curline(text);
+		txt_split_curline(text, utxt);
 		return true;
 	}
 	
 	/* insert spaces rather than tabs */
 	if (add == '\t' && replace_tabs) {
-		txt_convert_tab_to_spaces(text);
+		txt_convert_tab_to_spaces(text, utxt);
 		return true;
 	}
 
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 	
-	if (!undoing) txt_undo_add_charop(text, UNDO_INSERT_1, add);
+	if (!undoing) txt_undo_add_charop(text, utxt, UNDO_INSERT_1, add);
 
 	add_len = BLI_str_utf8_from_unicode(add, ch);
 	
@@ -2670,23 +2655,23 @@ static bool txt_add_char_intern(Text *text, unsigned int add, bool replace_tabs)
 	return 1;
 }
 
-bool txt_add_char(Text *text, unsigned int add)
+bool txt_add_char(Text *text, TextUndoBuf *utxt, unsigned int add)
 {
-	return txt_add_char_intern(text, add, (text->flags & TXT_TABSTOSPACES) != 0);
+	return txt_add_char_intern(text, utxt, add, (text->flags & TXT_TABSTOSPACES) != 0);
 }
 
-bool txt_add_raw_char(Text *text, unsigned int add)
+bool txt_add_raw_char(Text *text, TextUndoBuf *utxt, unsigned int add)
 {
-	return txt_add_char_intern(text, add, 0);
+	return txt_add_char_intern(text, utxt, add, 0);
 }
 
-void txt_delete_selected(Text *text)
+void txt_delete_selected(Text *text, TextUndoBuf *utxt)
 {
-	txt_delete_sel(text);
+	txt_delete_sel(text, utxt);
 	txt_make_dirty(text);
 }
 
-bool txt_replace_char(Text *text, unsigned int add)
+bool txt_replace_char(Text *text, TextUndoBuf *utxt, unsigned int add)
 {
 	unsigned int del;
 	size_t del_size = 0, add_size;
@@ -2696,7 +2681,7 @@ bool txt_replace_char(Text *text, unsigned int add)
 
 	/* If text is selected or we're at the end of the line just use txt_add_char */
 	if (text->curc == text->curl->len || txt_has_sel(text) || add == '\n') {
-		return txt_add_char(text, add);
+		return txt_add_char(text, utxt, add);
 	}
 	
 	del = BLI_str_utf8_as_unicode_and_size(text->curl->line + text->curc, &del_size);
@@ -2724,10 +2709,10 @@ bool txt_replace_char(Text *text, unsigned int add)
 
 	/* Should probably create a new op for this */
 	if (!undoing) {
-		txt_undo_add_charop(text, UNDO_INSERT_1, add);
+		txt_undo_add_charop(text, utxt, UNDO_INSERT_1, add);
 		text->curc -= add_size;
 		txt_pop_sel(text);
-		txt_undo_add_charop(text, UNDO_DEL_1, del);
+		txt_undo_add_charop(text, utxt, UNDO_DEL_1, del);
 		text->curc += add_size;
 		txt_pop_sel(text);
 	}
@@ -2867,7 +2852,7 @@ static void txt_select_unprefix(
 	/* caller must handle undo */
 }
 
-void txt_comment(Text *text)
+void txt_comment(Text *text, TextUndoBuf *utxt)
 {
 	const char *prefix = "#";
 
@@ -2878,11 +2863,11 @@ void txt_comment(Text *text)
 	txt_select_prefix(text, prefix);
 
 	if (!undoing) {
-		txt_undo_add_op(text, UNDO_COMMENT);
+		txt_undo_add_op(text, utxt, UNDO_COMMENT);
 	}
 }
 
-void txt_uncomment(Text *text)
+void txt_uncomment(Text *text, TextUndoBuf *utxt)
 {
 	const char *prefix = "#";
 	ListBase line_index_mask;
@@ -2895,13 +2880,13 @@ void txt_uncomment(Text *text)
 	txt_select_unprefix(text, prefix, &line_index_mask, &line_index_mask_len);
 
 	if (!undoing) {
-		txt_undo_add_unprefix_op(text, UNDO_UNCOMMENT, &line_index_mask, line_index_mask_len);
+		txt_undo_add_unprefix_op(text, utxt, UNDO_UNCOMMENT, &line_index_mask, line_index_mask_len);
 	}
 
 	BLI_freelistN(&line_index_mask);
 }
 
-void txt_indent(Text *text)
+void txt_indent(Text *text, TextUndoBuf *utxt)
 {
 	const char *prefix = (text->flags & TXT_TABSTOSPACES) ? tab_to_spaces : "\t";
 
@@ -2912,11 +2897,11 @@ void txt_indent(Text *text)
 	txt_select_prefix(text, prefix);
 
 	if (!undoing) {
-		txt_undo_add_op(text, UNDO_INDENT);
+		txt_undo_add_op(text, utxt, UNDO_INDENT);
 	}
 }
 
-void txt_unindent(Text *text)
+void txt_unindent(Text *text, TextUndoBuf *utxt)
 {
 	const char *prefix = (text->flags & TXT_TABSTOSPACES) ? tab_to_spaces : "\t";
 	ListBase line_index_mask;
@@ -2929,13 +2914,13 @@ void txt_unindent(Text *text)
 	txt_select_unprefix(text, prefix, &line_index_mask, &line_index_mask_len);
 
 	if (!undoing) {
-		txt_undo_add_unprefix_op(text, UNDO_UNINDENT, &line_index_mask, line_index_mask_len);
+		txt_undo_add_unprefix_op(text, utxt, UNDO_UNINDENT, &line_index_mask, line_index_mask_len);
 	}
 
 	BLI_freelistN(&line_index_mask);
 }
 
-void txt_move_lines(struct Text *text, const int direction)
+void txt_move_lines(struct Text *text, TextUndoBuf *utxt, const int direction)
 {
 	TextLine *line_other;
 
@@ -2962,7 +2947,7 @@ void txt_move_lines(struct Text *text, const int direction)
 	txt_clean_text(text);
 	
 	if (!undoing) {
-		txt_undo_add_op(text, (direction == TXT_MOVE_LINE_DOWN) ? UNDO_MOVE_LINES_DOWN : UNDO_MOVE_LINES_UP);
+		txt_undo_add_op(text, utxt, (direction == TXT_MOVE_LINE_DOWN) ? UNDO_MOVE_LINES_DOWN : UNDO_MOVE_LINES_UP);
 	}
 }
 
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 2b053b3fb45..a4739240cb4 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -3712,15 +3712,11 @@ static void lib_link_text(FileData *fd, Main *main)
 static void direct_link_text(FileData *fd, Text *text)
 {
 	TextLine *ln;
-	
+
 	text->name = newdataadr(fd, text->name);
-	
-	text->undo_pos = -1;
-	text->undo_len = TXT_INIT_UNDO;
-	text->undo_buf = MEM_mallocN(text->undo_len, "undo buf");
-	
+
 	text->compiled = NULL;
-	
+
 #if 0
 	if (text->flags & TXT_ISEXT) {
 		BKE_text_reload(text);
diff --git a/source/blender/editors/include/ED_text.h b/source/blender/editors/include/ED_text.h
index 5517e50aef4..763fbe3bac5 100644
--- a/source/blender/editors/include/ED_text.h
+++ b/source/blender/editors/include/ED_text.h
@@ -33,10 +33,13 @@
 struct SpaceText;
 struct ARegion;
 struct UndoType;
+struct TextUndoBuf;
 
 bool ED_text_region_location_from_cursor(struct SpaceText *st, struct ARegion *ar, const int cursor_co[2], int r_pixel_co[2]);
 
 /* text_undo.c */
 void ED_text_undosys_type(struct UndoType *ut);
 
+struct TextUndoBuf *ED_text_undo_push_init(struct bContext *C);
+
 #endif /* __ED_TEXT_H__ */
diff --git a/source/blender/editors/interface/interface_ops.c b/source/blender/editors/interface/interface_ops.c
index 7cf8a315895..046bb114a62 100644
--- a/source/blender/editors/interface/interface_ops.c
+++ b/source/blender/editors/interface/interface_ops.c
@@ -611,7 +611,8 @@ static int reports_to_text_exec(bContext *C, wmOperator *UNUSED(op))
 	str = BKE_reports_string(reports, (G.debug & G_DEBUG) ? RPT_DEBUG : RPT_INFO);
 
 	if (str) {
-		BKE_text_write(txt, str);
+		TextUndoBuf *utxt = NULL; // FIXME
+		BKE_text_write(txt, utxt, str);
 		MEM_freeN(str);
 
 		return OPERATOR_FINISHED;
diff --git a/source/blender/editors/space_text/text_autocomplete.c b/source/blender/editors/space_text/text_autocomplete.c
index da5fa9da046..9163831c333 100644
--- a/source/blender/editors/space_text/text_autocomplete.c
+++ b/source/blender/editors/space_text/text_autocomplete.c
@@ -241,7 +241,7 @@ static void get_suggest_prefix(Text *text, int offset)
 	texttool_suggest_prefix(line + i, len);
 }
 
-static void confirm_suggestion(Text *text)
+static void confirm_suggestion(Text *text, TextUndoBuf *utxt)
 {
 	SuggItem *sel;
 	int i, over = 0;
@@ -260,7 +260,7 @@ static void confirm_suggestion(Text *text)
 //	for (i = 0; i < skipleft; i++)
 //		txt_move_left(text, 0);
 	BLI_assert(memcmp(sel->name, &line[i], over) == 0);
-	txt_insert_buf(text, sel->name + over);
+	txt_insert_buf(text, utxt, sel->name + over);
 
 //	for (i = 0; i < skipleft; i++)
 //		txt_move_right(text, 0);
@@ -284,7 +284,8 @@ static int text_autocomplete_invoke(bContext *C, wmOperator *op, const wmEvent *
 		ED_area_tag_redraw(CTX_wm_area(C));
 
 		if (texttool_suggest_first() == texttool_suggest_last()) {
-			confirm_suggestion(st->text);
+			TextUndoBuf *utxt = NULL; // FIXME
+			confirm_suggestion(st->text, utxt);
 			text_update_line_edited(st->text->curl);
 			text_autocomplete_free(C, op);
 			return OPERATOR_FINISHED;
@@ -314,6 +315,8 @@ static int text_autocomplete_modal(bContext *C, wmOperator *op, const wmEvent *e
 
 	(void)text;
 
+	TextUndoBuf *utxt = NULL; // FIXME
+
 	if (st->doplugins && texttool_text_is_active(st->text)) {
 		if (texttool_suggest_first()) tools |= TOOL_SUGG_LIST;
 		if (texttool_docs_get()) tools |= TOOL_DOCUMENT;
@@ -340,7 +343,7 @@ static int text_autocomplete_modal(bContext *C, wmOperator *op, const wmEvent *e
 		case MIDDLEMOUSE:
 			if (event->val == KM_PRESS) {
 				if (text_do_suggest_select(st, ar)) {
-					confirm_suggestion(st->text);
+					confirm_suggestion(st->text, utxt);
 					text_update_line_edited(st->text->curl);
 					swallow = 1;
 				}
@@ -375,7 +378,7 @@ static int text_autocomplete_modal(bContext *C, wmOperator *op, const wmEvent *e
 		case PADENTER:
 			if (event->val == KM_PRESS) {
 				if (tools & TOOL_SUGG_LIST) {
-					confirm_suggestion(st->text);
+					confirm_suggestion(st->text, utxt);
 					text_update_line_edited(st->text->curl);
 					swallow = 1;
 					draw = 1;
diff --git a/source/blender/editors/space_text/text_ops.c b/source/blender/editors/space_text/text_ops.c
index 7580f22321b..223a3031f3b 100644
--- a/source/blender/editors/space_text/text_ops.c
+++ b/source/blender/editors/space_text/text_ops.c
@@ -731,7 +731,8 @@ static int text_paste_exec(bContext *C, wmOperator *op)
 
 	text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
-	txt_insert_buf(text, buf);
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+	txt_insert_buf(text, utxt, buf);
 	text_update_edited(text);
 
 	MEM_freeN(buf);
@@ -769,9 +770,11 @@ void TEXT_OT_paste(wmOperatorType *ot)
 static int text_duplicate_line_exec(bContext *C, wmOperator *UNUSED(op))
 {
 	Text *text = CTX_data_edit_text(C);
-	
-	txt_duplicate_line(text);
-	
+
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
+	txt_duplicate_line(text, utxt);
+
 	WM_event_add_notifier(C, NC_TEXT | NA_EDITED, text);
 
 	/* run the script while editing, evil but useful */
@@ -844,7 +847,9 @@ static int text_cut_exec(bContext *C, wmOperator *UNUSED(op))
 	text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
 	txt_copy_clipboard(text);
-	txt_delete_selected(text);
+
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+	txt_delete_selected(text, utxt);
 
 	text_update_cursor_moved(C);
 	WM_event_add_notifier(C, NC_TEXT | NA_EDITED, text);
@@ -879,12 +884,15 @@ static int text_indent_exec(bContext *C, wmOperator *UNUSED(op))
 
 	text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 	if (txt_has_sel(text)) {
 		txt_order_cursors(text, false);
-		txt_indent(text);
+		txt_indent(text, utxt);
+	}
+	else {
+		txt_add_char(text, utxt, '\t');
 	}
-	else
-		txt_add_char(text, '\t');
 
 	text_update_edited(text);
 
@@ -917,8 +925,10 @@ static int text_unindent_exec(bContext *C, wmOperator *UNUSED(op))
 
 	text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 	txt_order_cursors(text, false);
-	txt_unindent(text);
+	txt_unindent(text, utxt);
 
 	text_update_edited(text);
 
@@ -956,14 +966,15 @@ static int text_line_break_exec(bContext *C, wmOperator *UNUSED(op))
 
 	// double check tabs/spaces before splitting the line
 	curts = txt_setcurr_tab_spaces(text, space);
-	txt_split_curline(text);
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+	txt_split_curline(text, utxt);
 
 	for (a = 0; a < curts; a++) {
 		if (text->flags & TXT_TABSTOSPACES) {
-			txt_add_char(text, ' ');
+			txt_add_char(text, utxt, ' ');
 		}
 		else {
-			txt_add_char(text, '\t');
+			txt_add_char(text, utxt, '\t');
 		}
 	}
 
@@ -1003,8 +1014,10 @@ static int text_comment_exec(bContext *C, wmOperator *UNUSED(op))
 	if (txt_has_sel(text)) {
 		text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
+		TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 		txt_order_cursors(text, false);
-		txt_comment(text);
+		txt_comment(text, utxt);
 		text_update_edited(text);
 
 		text_update_cursor_moved(C);
@@ -1039,8 +1052,10 @@ static int text_uncomment_exec(bContext *C, wmOperator *UNUSED(op))
 	if (txt_has_sel(text)) {
 		text_drawcache_tag_update(CTX_wm_space_text(C), 0);
 
+		TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 		txt_order_cursors(text, false);
-		txt_uncomment(text);
+		txt_uncomment(text, utxt);
 		text_update_edited(text);
 
 		text_update_cursor_moved(C);
@@ -1292,8 +1307,10 @@ static int move_lines_exec(bContext *C, wmOperator *op)
 {
 	Text *text = CTX_data_edit_text(C);
 	const int direction = RNA_enum_get(op->ptr, "direction");
-	
-	txt_move_lines(text, direction);
+
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
+	txt_move_lines(text, utxt, direction);
 	
 	text_update_cursor_moved(C);
 	WM_event_add_notifier(C, NC_TEXT | NA_EDITED, text);
@@ -1966,6 +1983,7 @@ static int text_delete_exec(bContext *C, wmOperator *op)
 	Text *text = CTX_data_edit_text(C);
 	int type = RNA_enum_get(op->ptr, "type");
 
+
 	text_drawcache_tag_update(st, 0);
 
 	/* behavior could be changed here,
@@ -1975,11 +1993,13 @@ static int text_delete_exec(bContext *C, wmOperator *op)
 		else if (type == DEL_NEXT_WORD) type = DEL_NEXT_CHAR;
 	}
 
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 	if (type == DEL_PREV_WORD) {
 		if (txt_cursor_is_line_start(text)) {
-			txt_backspace_char(text);
+			txt_backspace_char(text, utxt);
 		}
-		txt_backspace_word(text);
+		txt_backspace_word(text, utxt);
 	}
 	else if (type == DEL_PREV_CHAR) {
 
@@ -1995,13 +2015,13 @@ static int text_delete_exec(bContext *C, wmOperator *op)
 			}
 		}
 
-		txt_backspace_char(text);
+		txt_backspace_char(text, utxt);
 	}
 	else if (type == DEL_NEXT_WORD) {
 		if (txt_cursor_is_line_end(text)) {
-			txt_delete_char(text);
+			txt_delete_char(text, utxt);
 		}
-		txt_delete_word(text);
+		txt_delete_word(text, utxt);
 	}
 	else if (type == DEL_NEXT_CHAR) {
 
@@ -2017,7 +2037,7 @@ static int text_delete_exec(bContext *C, wmOperator *op)
 			}
 		}
 
-		txt_delete_char(text);
+		txt_delete_char(text, utxt);
 	}
 
 	text_update_line_edited(text->curl);
@@ -2870,16 +2890,18 @@ static int text_insert_exec(bContext *C, wmOperator *op)
 
 	str = RNA_string_get_alloc(op->ptr, "text", NULL, 0);
 
+	TextUndoBuf *utxt = ED_text_undo_push_init(C);
+
 	if (st && st->overwrite) {
 		while (str[i]) {
 			code = BLI_str_utf8_as_unicode_step(str, &i);
-			done |= txt_replace_char(text, code);
+			done |= txt_replace_char(text, utxt, code);
 		}
 	}
 	else {
 		while (str[i]) {
 			code = BLI_str_utf8_as_unicode_step(str, &i);
-			done |= txt_add_char(text, code);
+			done |= txt_add_char(text, utxt, code);
 		}
 	}
 
@@ -2988,7 +3010,8 @@ static int text_find_and_replace(bContext *C, wmOperator *op, short mode)
 
 		if (found) {
 			if (mode == TEXT_REPLACE) {
-				txt_insert_buf(text, st->replacestr);
+				TextUndoBuf *utxt = ED_text_undo_push_init(C);
+				txt_insert_buf(text, utxt, st->replacestr);
 				if (text->curl && text->curl->format) {
 					MEM_freeN(text->curl->format);
 					text->curl->format = NULL;
diff --git a/source/blender/editors/space_text/text_undo.c b/source/blender/editors/space_text/text_undo.c
index f977e2c0d4f..729522cc8f4 100644
--- a/source/blender/editors/space_text/text_undo.c
+++ b/source/blender/editors/space_text/text_undo.c
@@ -48,6 +48,7 @@
 #include "ED_text.h"
 #include "ED_curve.h"
 #include "ED_screen.h"
+#include "ED_undo.h"
 
 #include "UI_interface.h"
 #include "UI_resources.h"
@@ -63,11 +64,6 @@
 /* -------------------------------------------------------------------- */
 /** \name Implements ED Undo System
  * \{ */
-typedef struct TextUndoBuf {
-	char *buf;
-	int len;
-	int pos;
-} TextUndoBuf;
 
 typedef struct TextUndoStep {
 	UndoStep step;
@@ -87,29 +83,33 @@ static bool text_undosys_poll(bContext *C)
 	return true;
 }
 
-static bool text_undosys_step_encode(struct bContext *C, UndoStep *us_p)
+static void text_undosys_step_encode_init(struct bContext *C, UndoStep *us_p)
 {
 	TextUndoStep *us = (TextUndoStep *)us_p;
 	BLI_assert(BLI_array_is_zeroed(&us->data, 1));
 
+	UNUSED_VARS(C);
+	/* XXX, use to set the undo type only. */
+
+	us->data.buf = NULL;
+	us->data.len = 0;
+	us->data.pos = -1;
+}
+
+static bool text_undosys_step_encode(struct bContext *C, UndoStep *us_p)
+{
+	TextUndoStep *us = (TextUndoStep *)us_p;
+
 	Text *text = CTX_data_edit_text(C);
 
 	/* No undo data was generated. Hint, use global undo here. */
-	if (text->undo_pos == -1) {
+	if ((us->data.pos == -1) || (us->data.buf == NULL)) {
 		return false;
 	}
 
 	us->text_ref.ptr = text;
 
-	us->data.buf = text->undo_buf;
-	us->data.pos = text->undo_pos;
-	us->data.len = text->undo_len;
-
-	text->undo_buf = NULL;
-	text->undo_len = 0;
-	text->undo_pos = -1;
-
-	us->step.data_size = text->undo_len;
+	us->step.data_size = us->data.len;
 
 	return true;
 }
@@ -119,20 +119,15 @@ static void text_undosys_step_decode(struct bContext *C, UndoStep *us_p, int dir
 	TextUndoStep *us = (TextUndoStep *)us_p;
 	Text *text = us->text_ref.ptr;
 
-	/* TODO(campbell): undo_system: move undo out of Text data block. */
-	text->undo_buf = us->data.buf;
-	text->undo_len = us->data.len;
 	if (dir < 0) {
-		text->undo_pos = us->data.pos;
-		txt_do_undo(text);
+		TextUndoBuf data = us->data;
+		txt_do_undo(text, &data);
 	}
 	else {
-		text->undo_pos = -1;
-		txt_do_redo(text);
+		TextUndoBuf data = us->data;
+		data.pos = -1;
+		txt_do_redo(text, &data);
 	}
-	text->undo_buf = NULL;
-	text->undo_len = 0;
-	text->undo_pos = -1;
 
 	text_update_edited(text);
 	text_update_cursor_moved(C);
@@ -159,6 +154,7 @@ void ED_text_undosys_type(UndoType *ut)
 {
 	ut->name = "Text";
 	ut->poll = text_undosys_poll;
+	ut->step_encode_init = text_undosys_step_encode_init;
 	ut->step_encode = text_undosys_step_encode;
 	ut->step_decode = text_undosys_step_decode;
 	ut->step_free = text_undosys_step_free;
@@ -166,9 +162,24 @@ void ED_text_undosys_type(UndoType *ut)
 	ut->step_foreach_ID_ref = text_undosys_foreach_ID_ref;
 
 	ut->mode = BKE_UNDOTYPE_MODE_ACCUMULATE;
-	ut->use_context = true;
+	ut->use_context = false;
 
 	ut->step_size = sizeof(TextUndoStep);
 }
 
 /** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Utilities
+ * \{ */
+
+/* Use operator system to finish the undo step. */
+TextUndoBuf *ED_text_undo_push_init(bContext *C)
+{
+	UndoStack *ustack = ED_undo_stack_get();
+	UndoStep *us_p = BKE_undosys_step_push_init_with_type(ustack, C, NULL, BKE_UNDOSYS_TYPE_TEXT);
+	TextUndoStep *us = (TextUndoStep *)us_p;
+	return &us->data;
+}
+
+/** \} */
diff --git a/source/blender/editors/undo/undo_system_types.c b/source/blender/editors/undo/undo_system_types.c
index f1ef444337c..4dbd22d6d22 100644
--- a/source/blender/editors/undo/undo_system_types.c
+++ b/source/blender/editors/undo/undo_system_types.c
@@ -62,7 +62,7 @@ void ED_undosys_type_init(void)
 	BKE_UNDOSYS_TYPE_PAINTCURVE = BKE_undosys_type_append(ED_paintcurve_undosys_type);
 
 	/* Text editor */
-	BKE_undosys_type_append(ED_text_undosys_type);
+	BKE_UNDOSYS_TYPE_TEXT = BKE_undosys_type_append(ED_text_undosys_type);
 
 	/* Keep global undo last (as a fallback). */
 	BKE_UNDOSYS_TYPE_MEMFILE = BKE_undosys_type_append(ED_memfile_undosys_type);
diff --git a/source/blender/makesdna/DNA_text_types.h b/source/blender/makesdna/DNA_text_types.h
index 17ef098a3bb..163dda678d9 100644
--- a/source/blender/makesdna/DNA_text_types.h
+++ b/source/blender/makesdna/DNA_text_types.h
@@ -59,10 +59,6 @@ typedef struct Text {
 	TextLine *curl, *sell;
 	int curc, selc;
 	
-	char *undo_buf;
-	void *pad;
-	int undo_pos, undo_len;
-	
 	double mtime;
 } Text;
 
diff --git a/source/blender/makesrna/intern/rna_text_api.c b/source/blender/makesrna/intern/rna_text_api.c
index 0287f74587b..d7a862fecbc 100644
--- a/source/blender/makesrna/intern/rna_text_api.c
+++ b/source/blender/makesrna/intern/rna_text_api.c
@@ -40,13 +40,13 @@
 
 static void rna_Text_clear(Text *text)
 {
-	BKE_text_clear(text);
+	BKE_text_clear(text, NULL);
 	WM_main_add_notifier(NC_TEXT | NA_EDITED, text);
 }
 
 static void rna_Text_write(Text *text, const char *str)
 {
-	BKE_text_write(text, str);
+	BKE_text_write(text, NULL, str);
 	WM_main_add_notifier(NC_TEXT | NA_EDITED, text);
 }