Code cleanup: remove WM subwindows.

These no longer made much sense after regions were added, they just
duplicated state that was already in the regions.

11 files changed, 124 insertions, 413 deletions

diff --git a/source/blender/windowmanager/CMakeLists.txt b/source/blender/windowmanager/CMakeLists.txt
index 059055daea9..0da45202730 100644
--- a/source/blender/windowmanager/CMakeLists.txt
+++ b/source/blender/windowmanager/CMakeLists.txt
@@ -93,7 +93,6 @@ set(SRC
 	wm_event_system.h
 	wm_event_types.h
 	wm_files.h
-	wm_subwindow.h
 	wm_window.h
 	manipulators/WM_manipulator_api.h
 	manipulators/WM_manipulator_types.h
diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 7e2dead52ee..f8e99edfbc9 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -457,15 +457,17 @@ struct wmDropBox	*WM_dropbox_add(ListBase *lb, const char *idname, int (*poll)(s
                                     void (*copy)(struct wmDrag *, struct wmDropBox *));
 ListBase	*WM_dropboxmap_find(const char *idname, int spaceid, int regionid);
 
-			/* Set a subwindow active in pixelspace view, with optional scissor subset */
-void		wmSubWindowSet			(struct wmWindow *win, int swinid);
-void		wmSubWindowScissorSet	(struct wmWindow *win, int swinid, const struct rcti *srct, bool srct_pad);
+			/* Set OpenGL viewport and scissor */
+void		wmViewport(const struct rcti *rect);
+void		wmPartialViewport(rcti *drawrct, const rcti *winrct, const rcti *partialrct);
+void		wmWindowViewport(struct wmWindow *win);
 
 			/* OpenGL utilities with safety check */
 void		wmOrtho2			(float x1, float x2, float y1, float y2);
 			/* use for conventions (avoid hard-coded offsets all over) */
 void		wmOrtho2_region_pixelspace(const struct ARegion *ar);
 void		wmOrtho2_pixelspace(const float x, const float y);
+void		wmGetProjectionMatrix(float mat[4][4], const struct rcti *winrct);
 
 			/* threaded Jobs Manager */
 enum {
diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index 46dad424cec..a09814cf5dd 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -115,6 +115,7 @@ struct ImBuf;
 
 #include "RNA_types.h"
 #include "DNA_listBase.h"
+#include "DNA_vec_types.h"
 #include "BLI_compiler_attrs.h"
 
 /* exported types for WM */
@@ -214,7 +215,6 @@ typedef struct wmNotifier {
 	struct wmWindowManager *wm;
 	struct wmWindow *window;
 	
-	int swinid;			/* can't rely on this, notifiers can be added without context, swinid of 0 */
 	unsigned int category, data, subtype, action;
 	
 	void *reference;
@@ -422,7 +422,7 @@ typedef struct wmGesture {
 	struct wmGesture *next, *prev;
 	int event_type;	/* event->type */
 	int type;		/* gesture type define */
-	int swinid;		/* initial subwindow id where it started */
+	rcti winrct;    /* bounds of region to draw gesture within */
 	int points;		/* optional, amount of points stored */
 	int points_alloc;	/* optional, maximum amount of points stored */
 	int modal_state;
diff --git a/source/blender/windowmanager/intern/wm_draw.c b/source/blender/windowmanager/intern/wm_draw.c
index eaee2dae3ac..4a6bc2ded28 100644
--- a/source/blender/windowmanager/intern/wm_draw.c
+++ b/source/blender/windowmanager/intern/wm_draw.c
@@ -95,7 +95,7 @@ static void wm_paintcursor_draw(bContext *C, ARegion *ar)
 		bScreen *screen = WM_window_get_active_screen(win);
 		wmPaintCursor *pc;
 
-		if (ar->swinid && screen->subwinactive == ar->swinid) {
+		if (ar->visible && ar == screen->active_region) {
 			for (pc = wm->paintcursors.first; pc; pc = pc->next) {
 				if (pc->poll == NULL || pc->poll(C)) {
 					ARegion *ar_other = CTX_wm_region(C);
@@ -216,7 +216,7 @@ static void wm_method_draw_full(bContext *C, wmWindow *win)
 		CTX_wm_area_set(C, sa);
 
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid) {
+			if (ar->visible) {
 				CTX_wm_region_set(C, ar);
 				ED_region_do_draw(C, ar);
 				ar->do_draw = false;
@@ -235,7 +235,7 @@ static void wm_method_draw_full(bContext *C, wmWindow *win)
 
 	/* draw overlapping regions */
 	for (ar = screen->regionbase.first; ar; ar = ar->next) {
-		if (ar->swinid) {
+		if (ar->visible) {
 			CTX_wm_menu_set(C, ar);
 			ED_region_do_draw(C, ar);
 			ar->do_draw = false;
@@ -295,7 +295,7 @@ static void wm_method_draw_overlap_all(bContext *C, wmWindow *win, int exchange)
 	/* after backbuffer selection draw, we need to redraw */
 	for (sa = screen->areabase.first; sa; sa = sa->next)
 		for (ar = sa->regionbase.first; ar; ar = ar->next)
-			if (ar->swinid && !wm_area_test_invalid_backbuf(sa))
+			if (ar->visible && !wm_area_test_invalid_backbuf(sa))
 				ED_region_tag_redraw(ar);
 
 	/* flush overlapping regions */
@@ -303,17 +303,17 @@ static void wm_method_draw_overlap_all(bContext *C, wmWindow *win, int exchange)
 		/* flush redraws of area regions up to overlapping regions */
 		for (sa = screen->areabase.first; sa; sa = sa->next)
 			for (ar = sa->regionbase.first; ar; ar = ar->next)
-				if (ar->swinid && ar->do_draw)
+				if (ar->visible && ar->do_draw)
 					wm_flush_regions_up(screen, &ar->winrct);
 		
 		/* flush between overlapping regions */
 		for (ar = screen->regionbase.last; ar; ar = ar->prev)
-			if (ar->swinid && ar->do_draw)
+			if (ar->visible && ar->do_draw)
 				wm_flush_regions_up(screen, &ar->winrct);
 		
 		/* flush redraws of overlapping regions down to area regions */
 		for (ar = screen->regionbase.last; ar; ar = ar->prev)
-			if (ar->swinid && ar->do_draw)
+			if (ar->visible && ar->do_draw)
 				wm_flush_regions_down(screen, &ar->winrct);
 	}
 
@@ -332,7 +332,7 @@ static void wm_method_draw_overlap_all(bContext *C, wmWindow *win, int exchange)
 		CTX_wm_area_set(C, sa);
 
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid) {
+			if (ar->visible) {
 				if (ar->do_draw) {
 					CTX_wm_region_set(C, ar);
 					ED_region_do_draw(C, ar);
@@ -389,7 +389,7 @@ static void wm_method_draw_overlap_all(bContext *C, wmWindow *win, int exchange)
 
 	/* draw marked overlapping regions */
 	for (ar = screen->regionbase.first; ar; ar = ar->next) {
-		if (ar->swinid && ar->do_draw) {
+		if (ar->visible && ar->do_draw) {
 			CTX_wm_menu_set(C, ar);
 			ED_region_do_draw(C, ar);
 			ar->do_draw = false;
@@ -526,9 +526,7 @@ static void wm_draw_region_blend(wmWindow *win, ARegion *ar, wmDrawTriple *tripl
 	
 	/* region blend always is 1, except when blend timer is running */
 	if (fac < 1.0f) {
-		bScreen *screen = WM_window_get_active_screen(win);
-
-		wmSubWindowScissorSet(win, screen->mainwin, &ar->winrct, true);
+		wmViewport(&ar->winrct);
 
 		glEnable(GL_BLEND);
 		wm_triple_draw_textures(win, triple, 1.0f - fac);
@@ -551,7 +549,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 #endif
 
-		wmSubWindowSet(win, screen->mainwin);
+		wmWindowViewport(win);
 
 		wm_triple_draw_textures(win, drawdata->triple, 1.0f);
 	}
@@ -587,7 +585,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 		CTX_wm_area_set(C, sa);
 
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid && ar->do_draw) {
+			if (ar->visible && ar->do_draw) {
 				if (ar->overlap == false) {
 					CTX_wm_region_set(C, ar);
 					ED_region_do_draw(C, ar);
@@ -603,7 +601,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 	}
 
 	if (copytex) {
-		wmSubWindowSet(win, screen->mainwin);
+		wmWindowViewport(win);
 
 		wm_triple_copy_textures(win, triple);
 	}
@@ -611,12 +609,12 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 	if (wm->paintcursors.first) {
 		for (sa = screen->areabase.first; sa; sa = sa->next) {
 			for (ar = sa->regionbase.first; ar; ar = ar->next) {
-				if (ar->swinid && ar->swinid == screen->subwinactive) {
+				if (ar->visible && ar == screen->active_region) {
 					CTX_wm_area_set(C, sa);
 					CTX_wm_region_set(C, ar);
 
 					/* make region ready for draw, scissor, pixelspace */
-					wmSubWindowScissorSet(win, ar->swinid, &ar->winrct, true);
+					wmViewport(&ar->winrct);
 					wm_paintcursor_draw(C, ar);
 
 					CTX_wm_region_set(C, NULL);
@@ -625,7 +623,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 			}
 		}
 
-		wmSubWindowSet(win, screen->mainwin);
+		wmWindowViewport(win);
 	}
 
 	/* draw overlapping area regions (always like popups) */
@@ -633,7 +631,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 		CTX_wm_area_set(C, sa);
 
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid && ar->overlap) {
+			if (ar->visible && ar->overlap) {
 				CTX_wm_region_set(C, ar);
 				ED_region_do_draw(C, ar);
 				ar->do_draw = false;
@@ -653,7 +651,7 @@ static void wm_method_draw_triple(bContext *C, wmWindow *win)
 
 	/* draw floating regions (menus) */
 	for (ar = screen->regionbase.first; ar; ar = ar->next) {
-		if (ar->swinid) {
+		if (ar->visible) {
 			CTX_wm_menu_set(C, ar);
 			ED_region_do_draw(C, ar);
 			ar->do_draw = false;
@@ -693,7 +691,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 				glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 #endif
 
-				wmSubWindowSet(win, screen->mainwin);
+				wmWindowViewport(win);
 
 				wm_triple_draw_textures(win, drawdata->triple, 1.0f);
 			}
@@ -758,7 +756,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 
 		/* draw marked area regions */
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid && ar->do_draw) {
+			if (ar->visible && ar->do_draw) {
 
 				if (ar->overlap == false) {
 					CTX_wm_region_set(C, ar);
@@ -778,7 +776,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 	}
 
 	if (copytex) {
-		wmSubWindowSet(win, screen->mainwin);
+		wmWindowViewport(win);
 
 		wm_triple_copy_textures(win, triple_data);
 	}
@@ -786,12 +784,12 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 	if (wm->paintcursors.first) {
 		for (sa = screen->areabase.first; sa; sa = sa->next) {
 			for (ar = sa->regionbase.first; ar; ar = ar->next) {
-				if (ar->swinid && ar->swinid == screen->subwinactive) {
+				if (ar->visible && ar == screen->active_region) {
 					CTX_wm_area_set(C, sa);
 					CTX_wm_region_set(C, ar);
 
 					/* make region ready for draw, scissor, pixelspace */
-					wmSubWindowScissorSet(win, ar->swinid, &ar->winrct, true);
+					wmViewport(&ar->winrct);
 					wm_paintcursor_draw(C, ar);
 
 					CTX_wm_region_set(C, NULL);
@@ -800,7 +798,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 			}
 		}
 
-		wmSubWindowSet(win, screen->mainwin);
+		wmWindowViewport(win);
 	}
 
 	/* draw overlapping area regions (always like popups) */
@@ -808,7 +806,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 		CTX_wm_area_set(C, sa);
 
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
-			if (ar->swinid && ar->overlap) {
+			if (ar->visible && ar->overlap) {
 				CTX_wm_region_set(C, ar);
 				ED_region_do_draw(C, ar);
 				if (sview == STEREO_RIGHT_ID)
@@ -831,7 +829,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 
 	/* draw floating regions (menus) */
 	for (ar = screen->regionbase.first; ar; ar = ar->next) {
-		if (ar->swinid) {
+		if (ar->visible) {
 			CTX_wm_menu_set(C, ar);
 			ED_region_do_draw(C, ar);
 			if (sview == STEREO_RIGHT_ID)
@@ -850,7 +848,7 @@ static void wm_method_draw_triple_multiview(bContext *C, wmWindow *win, eStereoV
 	}
 
 	/* copy the ui + overlays */
-	wmSubWindowSet(win, screen->mainwin);
+	wmWindowViewport(win);
 	wm_triple_copy_textures(win, triple_all);
 }
 
@@ -873,7 +871,7 @@ static bool wm_draw_update_test_window(wmWindow *win)
 			wm_tag_redraw_overlay(win, ar);
 			ar->do_draw_overlay = false;
 		}
-		if (ar->swinid && ar->do_draw)
+		if (ar->visible && ar->do_draw)
 			do_draw = true;
 	}
 
@@ -881,7 +879,7 @@ static bool wm_draw_update_test_window(wmWindow *win)
 		for (ar = sa->regionbase.first; ar; ar = ar->next) {
 			wm_region_test_render_do_draw(scene, depsgraph, sa, ar);
 
-			if (ar->swinid && ar->do_draw)
+			if (ar->visible && ar->do_draw)
 				do_draw = true;
 		}
 	}
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 3bde9d46df3..38f9a2bccae 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -182,7 +182,6 @@ static bool wm_test_duplicate_notifier(wmWindowManager *wm, unsigned int type, v
 /* XXX: in future, which notifiers to send to other windows? */
 void WM_event_add_notifier(const bContext *C, unsigned int type, void *reference)
 {
-	ARegion *ar;
 	wmWindowManager *wm = CTX_wm_manager(C);
 	wmNotifier *note;
 
@@ -196,10 +195,6 @@ void WM_event_add_notifier(const bContext *C, unsigned int type, void *reference
 	
 	note->window = CTX_wm_window(C);
 	
-	ar = CTX_wm_region(C);
-	if (ar)
-		note->swinid = ar->swinid;
-	
 	note->category = type & NOTE_CATEGORY;
 	note->data = type & NOTE_DATA;
 	note->subtype = type & NOTE_SUBTYPE;
@@ -1209,8 +1204,8 @@ static int wm_operator_invoke(
 		}
 
 		if ((G.debug & G_DEBUG_HANDLERS) && ((event == NULL) || (event->type != MOUSEMOVE))) {
-			printf("%s: handle evt %d win %d op %s\n",
-			       __func__, event ? event->type : 0, CTX_wm_screen(C)->subwinactive, ot->idname);
+			printf("%s: handle evt %d region %p op %s\n",
+			       __func__, event ? event->type : 0, CTX_wm_screen(C)->active_region, ot->idname);
 		}
 		
 		if (op->type->invoke && event) {
@@ -2769,7 +2764,7 @@ void wm_event_do_handlers(bContext *C)
 				/* Note: setting subwin active should be done here, after modal handlers have been done */
 				if (event->type == MOUSEMOVE) {
 					/* state variables in screen, cursors. Also used in wm_draw.c, fails for modal handlers though */
-					ED_screen_set_subwinactive(C, event);
+					ED_screen_set_active_region(C, event);
 					/* for regions having custom cursors */
 					wm_paintcursor_test(C, event);
 				}
diff --git a/source/blender/windowmanager/intern/wm_gesture.c b/source/blender/windowmanager/intern/wm_gesture.c
index fa5fd38b7b2..28775050211 100644
--- a/source/blender/windowmanager/intern/wm_gesture.c
+++ b/source/blender/windowmanager/intern/wm_gesture.c
@@ -49,7 +49,6 @@
 #include "WM_types.h"
 
 #include "wm.h"
-#include "wm_subwindow.h"
 #include "wm_draw.h"
 
 #include "GPU_immediate.h"
@@ -64,40 +63,37 @@ wmGesture *WM_gesture_new(bContext *C, const wmEvent *event, int type)
 	wmGesture *gesture = MEM_callocN(sizeof(wmGesture), "new gesture");
 	wmWindow *window = CTX_wm_window(C);
 	ARegion *ar = CTX_wm_region(C);
-	int sx, sy;
 	
 	BLI_addtail(&window->gesture, gesture);
 	
 	gesture->type = type;
 	gesture->event_type = event->type;
-	gesture->swinid = ar->swinid;    /* means only in area-region context! */
+	gesture->winrct = ar->winrct;
 	gesture->userdata_free = true;   /* Free if userdata is set. */
 	gesture->modal_state = GESTURE_MODAL_NOP;
 	
-	wm_subwindow_origin_get(window, gesture->swinid, &sx, &sy);
-	
 	if (ELEM(type, WM_GESTURE_RECT, WM_GESTURE_CROSS_RECT, WM_GESTURE_TWEAK,
 	          WM_GESTURE_CIRCLE, WM_GESTURE_STRAIGHTLINE))
 	{
 		rcti *rect = MEM_callocN(sizeof(rcti), "gesture rect new");
 		
 		gesture->customdata = rect;
-		rect->xmin = event->x - sx;
-		rect->ymin = event->y - sy;
+		rect->xmin = event->x - gesture->winrct.xmin;
+		rect->ymin = event->y - gesture->winrct.ymin;
 		if (type == WM_GESTURE_CIRCLE) {
 			/* caller is responsible for initializing 'xmax' to radius. */
 		}
 		else {
-			rect->xmax = event->x - sx;
-			rect->ymax = event->y - sy;
+			rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymax = event->y - gesture->winrct.ymin;
 		}
 	}
 	else if (ELEM(type, WM_GESTURE_LINES, WM_GESTURE_LASSO)) {
 		short *lasso;
 		gesture->points_alloc = 1024;
 		gesture->customdata = lasso = MEM_mallocN(sizeof(short[2]) * gesture->points_alloc, "lasso points");
-		lasso[0] = event->x - sx;
-		lasso[1] = event->y - sy;
+		lasso[0] = event->x - gesture->winrct.xmin;
+		lasso[1] = event->y - gesture->winrct.ymin;
 		gesture->points = 1;
 	}
 	
@@ -273,14 +269,13 @@ static void draw_filled_lasso_px_cb(int x, int x_end, int y, void *user_data)
 	memset(col, 0x10, x_end - x);
 }
 
-static void draw_filled_lasso(wmWindow *win, wmGesture *gt)
+static void draw_filled_lasso(wmGesture *gt)
 {
 	const short *lasso = (short *)gt->customdata;
 	const int tot = gt->points;
 	int (*moves)[2] = MEM_mallocN(sizeof(*moves) * (tot + 1), __func__);
 	int i;
 	rcti rect;
-	rcti rect_win;
 	float red[4] = {1.0f, 0.0f, 0.0f, 0.0f};
 
 	for (i = 0; i < tot; i++, lasso += 2) {
@@ -290,10 +285,9 @@ static void draw_filled_lasso(wmWindow *win, wmGesture *gt)
 
 	BLI_lasso_boundbox(&rect, (const int (*)[2])moves, tot);
 
-	wm_subwindow_rect_get(win, gt->swinid, &rect_win);
-	BLI_rcti_translate(&rect, rect_win.xmin, rect_win.ymin);
-	BLI_rcti_isect(&rect_win, &rect, &rect);
-	BLI_rcti_translate(&rect, -rect_win.xmin, -rect_win.ymin);
+	BLI_rcti_translate(&rect, gt->winrct.xmin, gt->winrct.ymin);
+	BLI_rcti_isect(&gt->winrct, &rect, &rect);
+	BLI_rcti_translate(&rect, -gt->winrct.xmin, -gt->winrct.ymin);
 
 	/* highly unlikely this will fail, but could crash if (tot == 0) */
 	if (BLI_rcti_is_empty(&rect) == false) {
@@ -335,13 +329,13 @@ static void draw_filled_lasso(wmWindow *win, wmGesture *gt)
 }
 
 
-static void wm_gesture_draw_lasso(wmWindow *win, wmGesture *gt, bool filled)
+static void wm_gesture_draw_lasso(wmGesture *gt, bool filled)
 {
 	const short *lasso = (short *)gt->customdata;
 	int i;
 
 	if (filled) {
-		draw_filled_lasso(win, gt);
+		draw_filled_lasso(gt);
 	}
 
 	const int numverts = gt->points;
@@ -425,7 +419,7 @@ void wm_gesture_draw(wmWindow *win)
 	glLineWidth(1.0f);
 	for (; gt; gt = gt->next) {
 		/* all in subwindow space */
-		wmSubWindowSet(win, gt->swinid);
+		wmViewport(&gt->winrct);
 		
 		if (gt->type == WM_GESTURE_RECT)
 			wm_gesture_draw_rect(gt);
@@ -442,9 +436,9 @@ void wm_gesture_draw(wmWindow *win)
 			}
 		}
 		else if (gt->type == WM_GESTURE_LINES)
-			wm_gesture_draw_lasso(win, gt, false);
+			wm_gesture_draw_lasso(gt, false);
 		else if (gt->type == WM_GESTURE_LASSO)
-			wm_gesture_draw_lasso(win, gt, true);
+			wm_gesture_draw_lasso(gt, true);
 		else if (gt->type == WM_GESTURE_STRAIGHTLINE)
 			wm_gesture_draw_line(gt);
 	}
diff --git a/source/blender/windowmanager/intern/wm_gesture_ops.c b/source/blender/windowmanager/intern/wm_gesture_ops.c
index a554727cacd..01184f47920 100644
--- a/source/blender/windowmanager/intern/wm_gesture_ops.c
+++ b/source/blender/windowmanager/intern/wm_gesture_ops.c
@@ -47,7 +47,6 @@
 #include "wm.h"
 #include "wm_event_types.h"
 #include "wm_event_system.h"
-#include "wm_subwindow.h"
 
 #include "ED_screen.h"
 
@@ -198,18 +197,15 @@ int WM_gesture_border_modal(bContext *C, wmOperator *op, const wmEvent *event)
 {
 	wmGesture *gesture = op->customdata;
 	rcti *rect = gesture->customdata;
-	int sx, sy;
 
 	if (event->type == MOUSEMOVE) {
-		wm_subwindow_origin_get(CTX_wm_window(C), gesture->swinid, &sx, &sy);
-
 		if (gesture->type == WM_GESTURE_CROSS_RECT && gesture->is_active == false) {
-			rect->xmin = rect->xmax = event->x - sx;
-			rect->ymin = rect->ymax = event->y - sy;
+			rect->xmin = rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymin = rect->ymax = event->y - gesture->winrct.ymin;
 		}
 		else {
-			rect->xmax = event->x - sx;
-			rect->ymax = event->y - sy;
+			rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymax = event->y - gesture->winrct.ymin;
 		}
 		gesture_border_apply_rect(op);
 
@@ -333,13 +329,11 @@ int WM_gesture_circle_modal(bContext *C, wmOperator *op, const wmEvent *event)
 {
 	wmGesture *gesture = op->customdata;
 	rcti *rect = gesture->customdata;
-	int sx, sy;
 
 	if (event->type == MOUSEMOVE) {
-		wm_subwindow_origin_get(CTX_wm_window(C), gesture->swinid, &sx, &sy);
 
-		rect->xmin = event->x - sx;
-		rect->ymin = event->y - sy;
+		rect->xmin = event->x - gesture->winrct.xmin;
+		rect->ymin = event->y - gesture->winrct.ymin;
 
 		wm_gesture_tag_redraw(C);
 
@@ -464,24 +458,22 @@ static void gesture_tweak_modal(bContext *C, const wmEvent *event)
 	wmWindow *window = CTX_wm_window(C);
 	wmGesture *gesture = window->tweak;
 	rcti *rect = gesture->customdata;
-	int sx, sy, val;
+	int val;
 
 	switch (event->type) {
 		case MOUSEMOVE:
 		case INBETWEEN_MOUSEMOVE:
 
-			wm_subwindow_origin_get(window, gesture->swinid, &sx, &sy);
-
-			rect->xmax = event->x - sx;
-			rect->ymax = event->y - sy;
+			rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymax = event->y - gesture->winrct.ymin;
 
 			if ((val = wm_gesture_evaluate(gesture))) {
 				wmEvent tevent;
 
 				wm_event_init_from_window(window, &tevent);
 				/* We want to get coord from start of drag, not from point where it becomes a tweak event, see T40549 */
-				tevent.x = rect->xmin + sx;
-				tevent.y = rect->ymin + sy;
+				tevent.x = rect->xmin + gesture->winrct.xmin;
+				tevent.y = rect->ymin + gesture->winrct.ymin;
 				if (gesture->event_type == LEFTMOUSE)
 					tevent.type = EVT_TWEAK_L;
 				else if (gesture->event_type == RIGHTMOUSE)
@@ -617,7 +609,6 @@ static void gesture_lasso_apply(bContext *C, wmOperator *op)
 int WM_gesture_lasso_modal(bContext *C, wmOperator *op, const wmEvent *event)
 {
 	wmGesture *gesture = op->customdata;
-	int sx, sy;
 
 	switch (event->type) {
 		case MOUSEMOVE:
@@ -625,8 +616,6 @@ int WM_gesture_lasso_modal(bContext *C, wmOperator *op, const wmEvent *event)
 
 			wm_gesture_tag_redraw(C);
 
-			wm_subwindow_origin_get(CTX_wm_window(C), gesture->swinid, &sx, &sy);
-
 			if (gesture->points == gesture->points_alloc) {
 				gesture->points_alloc *= 2;
 				gesture->customdata = MEM_reallocN(gesture->customdata, sizeof(short[2]) * gesture->points_alloc);
@@ -637,15 +626,15 @@ int WM_gesture_lasso_modal(bContext *C, wmOperator *op, const wmEvent *event)
 				short *lasso = gesture->customdata;
 
 				lasso += (2 * gesture->points - 2);
-				x = (event->x - sx - lasso[0]);
-				y = (event->y - sy - lasso[1]);
+				x = (event->x - gesture->winrct.xmin - lasso[0]);
+				y = (event->y - gesture->winrct.ymin - lasso[1]);
 
 				/* make a simple distance check to get a smoother lasso
 				 * add only when at least 2 pixels between this and previous location */
 				if ((x * x + y * y) > 4) {
 					lasso += 2;
-					lasso[0] = event->x - sx;
-					lasso[1] = event->y - sy;
+					lasso[0] = event->x - gesture->winrct.xmin;
+					lasso[1] = event->y - gesture->winrct.ymin;
 					gesture->points++;
 				}
 			}
@@ -813,18 +802,15 @@ int WM_gesture_straightline_modal(bContext *C, wmOperator *op, const wmEvent *ev
 {
 	wmGesture *gesture = op->customdata;
 	rcti *rect = gesture->customdata;
-	int sx, sy;
 
 	if (event->type == MOUSEMOVE) {
-		wm_subwindow_origin_get(CTX_wm_window(C), gesture->swinid, &sx, &sy);
-
 		if (gesture->is_active == false) {
-			rect->xmin = rect->xmax = event->x - sx;
-			rect->ymin = rect->ymax = event->y - sy;
+			rect->xmin = rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymin = rect->ymax = event->y - gesture->winrct.ymin;
 		}
 		else {
-			rect->xmax = event->x - sx;
-			rect->ymax = event->y - sy;
+			rect->xmax = event->x - gesture->winrct.xmin;
+			rect->ymax = event->y - gesture->winrct.ymin;
 			gesture_straightline_apply(C, op);
 		}
 
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index 7637d222913..47df14cd647 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -3310,7 +3310,7 @@ static void redraw_timer_step(
 			CTX_wm_area_set(C, sa_iter);
 
 			for (ar_iter = sa_iter->regionbase.first; ar_iter; ar_iter = ar_iter->next) {
-				if (ar_iter->swinid) {
+				if (ar_iter->visible) {
 					CTX_wm_region_set(C, ar_iter);
 					ED_region_do_draw(C, ar_iter);
 					ar_iter->do_draw = false;
diff --git a/source/blender/windowmanager/intern/wm_subwindow.c b/source/blender/windowmanager/intern/wm_subwindow.c
index 17d69a13aff..5ca34880743 100644
--- a/source/blender/windowmanager/intern/wm_subwindow.c
+++ b/source/blender/windowmanager/intern/wm_subwindow.c
@@ -21,301 +21,89 @@
  * Contributor(s): 2007 Blender Foundation (refactor)
  *
  * ***** END GPL LICENSE BLOCK *****
- *
- *
- * Subwindow opengl handling. 
- * BTW: subwindows open/close in X11 are way too slow, tried it, and choose for my own system... (ton)
- * 
  */
 
 /** \file blender/windowmanager/intern/wm_subwindow.c
  *  \ingroup wm
  *
- * Internal subwindows used for OpenGL state, used for regions and screens.
+ * OpenGL utilities for setting up 2D viewport for window and regions.
  */
 
-#include <string.h>
-
-#include "MEM_guardedalloc.h"
+#include "BLI_math.h"
+#include "BLI_rect.h"
 
-#include "DNA_windowmanager_types.h"
 #include "DNA_screen_types.h"
-
-#include "BLI_blenlib.h"
-#include "BLI_math.h"
-#include "BLI_utildefines.h"
+#include "DNA_windowmanager_types.h"
 
 #include "BIF_gl.h"
 
 #include "GPU_matrix.h"
 
 #include "WM_api.h"
-#include "wm_subwindow.h"
-
-/**
- * \note #wmSubWindow stored in #wmWindow but not exposed outside this C file,
- * it seems a bit redundant (area regions can store it too, but we keep it
- * because we can store all kind of future opengl fanciness here.
- *
- * We use indices and array because:
- * - index has safety, no pointers from this C file hanging around
- * - fast lookups of indices with array, list would give overhead
- * - old code used it this way...
- * - keep option open to have 2 screens using same window
- */
-
-typedef struct wmSubWindow {
-	struct wmSubWindow *next, *prev;
-	
-	rcti winrct;
-	int swinid;
-} wmSubWindow;
-
-
-/* ******************* open, free, set, get data ******************** */
-
-/* not subwindow itself */
-static void wm_subwindow_free(wmSubWindow *UNUSED(swin))
-{
-	/* future fancy stuff */
-}
-
-void wm_subwindows_free(wmWindow *win)
-{
-	wmSubWindow *swin;
-	
-	for (swin = win->subwindows.first; swin; swin = swin->next)
-		wm_subwindow_free(swin);
-	
-	BLI_freelistN(&win->subwindows);
-}
-
-
-static wmSubWindow *swin_from_swinid(wmWindow *win, int swinid)
-{
-	wmSubWindow *swin;
-	
-	for (swin = win->subwindows.first; swin; swin = swin->next)
-		if (swin->swinid == swinid)
-			break;
-	return swin;
-}
-
 
-static void wm_swin_size_get(wmSubWindow *swin, int *x, int *y)
+void wmViewport(const rcti *winrct)
 {
-	*x = BLI_rcti_size_x(&swin->winrct) + 1;
-	*y = BLI_rcti_size_y(&swin->winrct) + 1;
-}
-void wm_subwindow_size_get(wmWindow *win, int swinid, int *x, int *y)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
+	int width  = BLI_rcti_size_x(winrct) + 1;
+	int height = BLI_rcti_size_y(winrct) + 1;
 
-	if (swin) {
-		wm_swin_size_get(swin, x, y);
-	}
-}
-
-
-static void wm_swin_origin_get(wmSubWindow *swin, int *x, int *y)
-{
-	*x = swin->winrct.xmin;
-	*y = swin->winrct.ymin;
-}
-void wm_subwindow_origin_get(wmWindow *win, int swinid, int *x, int *y)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
+	glViewport(winrct->xmin, winrct->ymin, width, height);
+	glScissor(winrct->xmin, winrct->ymin, width, height);
 
-	if (swin) {
-		wm_swin_origin_get(swin, x, y);
-	}
+	wmOrtho2_pixelspace(width, height);
+	gpuLoadIdentity();
 }
 
-
-static void wm_swin_matrix_get(wmWindow *win, wmSubWindow *swin, float mat[4][4])
+void wmPartialViewport(rcti *drawrct, const rcti *winrct, const rcti *partialrct)
 {
-	const bScreen *screen = WM_window_get_active_screen(win);
-
-	/* used by UI, should find a better way to get the matrix there */
-	if (swin->swinid == screen->mainwin) {
-		int width, height;
+	/* Setup part of the viewport for partial redraw. */
+	bool scissor_pad;
 
-		wm_swin_size_get(swin, &width, &height);
-		orthographic_m4(mat, -GLA_PIXEL_OFS, (float)width - GLA_PIXEL_OFS, -GLA_PIXEL_OFS, (float)height - GLA_PIXEL_OFS, -100, 100);
+	if (partialrct->xmin == partialrct->xmax) {
+		/* Full region. */
+		*drawrct = *winrct;
+		scissor_pad = true;
 	}
 	else {
-		gpuGetProjectionMatrix(mat);
-	}
-}
-void wm_subwindow_matrix_get(wmWindow *win, int swinid, float mat[4][4])
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
-
-	if (swin) {
-		wm_swin_matrix_get(win, swin, mat);
-	}
-}
-
-
-static void wm_swin_rect_get(wmSubWindow *swin, rcti *r_rect)
-{
-	*r_rect = swin->winrct;
-}
-void wm_subwindow_rect_get(wmWindow *win, int swinid, rcti *r_rect)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
-
-	if (swin) {
-		wm_swin_rect_get(swin, r_rect);
-	}
-}
-
-
-static void wm_swin_rect_set(wmSubWindow *swin, const rcti *rect)
-{
-	swin->winrct = *rect;
-}
-void wm_subwindow_rect_set(wmWindow *win, int swinid, const rcti *rect)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
-
-	if (swin) {
-		wm_swin_rect_set(swin, rect);
-	}
-}
-
-
-/* always sets pixel-precise 2D window/view matrices */
-/* coords is in whole pixels. xmin = 15, xmax = 16: means window is 2 pix big */
-int wm_subwindow_open(wmWindow *win, const rcti *winrct, bool activate)
-{
-	wmSubWindow *swin;
-	int width, height;
-	int freewinid = 1;
-	
-	for (swin = win->subwindows.first; swin; swin = swin->next)
-		if (freewinid <= swin->swinid)
-			freewinid = swin->swinid + 1;
-
-	swin = MEM_callocN(sizeof(wmSubWindow), "swinopen");
-	BLI_addtail(&win->subwindows, swin);
-	
-	swin->swinid = freewinid;
-	swin->winrct = *winrct;
-
-	if (activate) {
-		/* and we appy it all right away */
-		wmSubWindowSet(win, swin->swinid);
-
-		/* extra service */
-		wm_swin_size_get(swin, &width, &height);
-		wmOrtho2_pixelspace(width, height);
-		gpuLoadIdentity();
+		/* Partial redraw, clipped to region. */
+		BLI_rcti_isect(winrct, partialrct, drawrct);
+		scissor_pad = false;
 	}
 
-	return swin->swinid;
-}
+	int x = drawrct->xmin;
+	int y = drawrct->ymin;
+	int width  = BLI_rcti_size_x(winrct) + 1;
+	int height = BLI_rcti_size_y(winrct) + 1;
 
-void wm_subwindow_close(wmWindow *win, int swinid)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
+	int scissor_width  = BLI_rcti_size_x(drawrct);
+	int scissor_height = BLI_rcti_size_y(drawrct);
 
-	if (swin) {
-		wm_subwindow_free(swin);
-		BLI_remlink(&win->subwindows, swin);
-		MEM_freeN(swin);
+	/* Partial redraw rect uses different convention than region rect,
+	 * so compensate for that here. One pixel offset is noticeable with
+	 * viewport border render. */
+	if (scissor_pad) {
+		scissor_width  += 1;
+		scissor_height += 1;
 	}
-	else {
-		printf("%s: Internal error, bad winid: %d\n", __func__, swinid);
-	}
-}
 
-/* pixels go from 0-99 for a 100 pixel window */
-void wm_subwindow_position(wmWindow *win, int swinid, const rcti *winrct, bool activate)
-{
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
-	
-	if (swin) {
-		const int winsize_x = WM_window_pixels_x(win);
-		const int winsize_y = WM_window_pixels_y(win);
+	glViewport(x, y, width, height);
+	glScissor(x, y, scissor_width, scissor_height);
 
-		int width, height;
-		
-		swin->winrct = *winrct;
-		
-		/* CRITICAL, this clamping ensures that
-		 * the viewport never goes outside the screen
-		 * edges (assuming the x, y coords aren't
-		 *        outside). This caused a hardware lock
-		 * on Matrox cards if it happens.
-		 *
-		 * Really Blender should never _ever_ try
-		 * to do such a thing, but just to be safe
-		 * clamp it anyway (or fix the bScreen
-		 * scaling routine, and be damn sure you
-		 * fixed it). - zr  (2001!)
-		 */
-		
-		if (swin->winrct.xmax > winsize_x)
-			swin->winrct.xmax = winsize_x;
-		if (swin->winrct.ymax > winsize_y)
-			swin->winrct.ymax = winsize_y;
-		
-		if (activate) {
-			/* extra service */
-			wmSubWindowSet(win, swinid);
-			wm_swin_size_get(swin, &width, &height);
-			wmOrtho2_pixelspace(width, height);
-		}
-	}
-	else {
-		printf("%s: Internal error, bad winid: %d\n", __func__, swinid);
-	}
+	wmOrtho2_pixelspace(width, height);
+	gpuLoadIdentity();
 }
 
-/* ---------------- WM versions of OpenGL style API calls ------------------------ */
-/* ----------------- exported in WM_api.h ------------------------------------------------------ */
-
-void wmSubWindowScissorSet(wmWindow *win, int swinid, const rcti *srct, bool srct_pad)
+void wmWindowViewport(wmWindow *win)
 {
-	int width, height;
-	wmSubWindow *swin = swin_from_swinid(win, swinid);
-	
-	if (swin == NULL) {
-		printf("%s %d: doesn't exist\n", __func__, swinid);
-		return;
-	}
-	
-	width  = BLI_rcti_size_x(&swin->winrct) + 1;
-	height = BLI_rcti_size_y(&swin->winrct) + 1;
-	glViewport(swin->winrct.xmin, swin->winrct.ymin, width, height);
-	
-	if (srct) {
-		int scissor_width  = BLI_rcti_size_x(srct);
-		int scissor_height = BLI_rcti_size_y(srct);
+	int width = WM_window_pixels_x(win);
+	int height = WM_window_pixels_y(win);
 
-		/* typically a single pixel doesn't matter,
-		 * but one pixel offset is noticeable with viewport border render */
-		if (srct_pad) {
-			scissor_width  += 1;
-			scissor_height += 1;
-		}
+	glViewport(0, 0, width, height);
+	glScissor(0, 0, width, height);
 
-		glScissor(srct->xmin, srct->ymin, scissor_width, scissor_height);
-	}
-	else
-		glScissor(swin->winrct.xmin, swin->winrct.ymin, width, height);
-	
 	wmOrtho2_pixelspace(width, height);
 	gpuLoadIdentity();
 }
 
-/* enable the WM versions of opengl calls */
-void wmSubWindowSet(wmWindow *win, int swinid)
-{
-	wmSubWindowScissorSet(win, swinid, NULL, true);
-}
-
 void wmOrtho2(float x1, float x2, float y1, float y2)
 {
 	/* prevent opengl from generating errors */
@@ -330,9 +118,7 @@ static void wmOrtho2_offset(const float x, const float y, const float ofs)
 	wmOrtho2(ofs, x + ofs, ofs, y + ofs);
 }
 
-/**
- * default pixel alignment.
- */
+/* Default pixel alignment for regions. */
 void wmOrtho2_region_pixelspace(const ARegion *ar)
 {
 	wmOrtho2_offset(ar->winx, ar->winy, -0.01f);
@@ -343,5 +129,9 @@ void wmOrtho2_pixelspace(const float x, const float y)
 	wmOrtho2_offset(x, y, -GLA_PIXEL_OFS);
 }
 
-/* ********** END MY WINDOW ************** */
-
+void wmGetProjectionMatrix(float mat[4][4], const rcti *winrct)
+{
+	int width  = BLI_rcti_size_x(winrct) + 1;
+	int height = BLI_rcti_size_y(winrct) + 1;
+	orthographic_m4(mat, -GLA_PIXEL_OFS, (float)width - GLA_PIXEL_OFS, -GLA_PIXEL_OFS, (float)height - GLA_PIXEL_OFS, -100, 100);
+}
diff --git a/source/blender/windowmanager/intern/wm_window.c b/source/blender/windowmanager/intern/wm_window.c
index 0c2ac975ddd..9aecee75a15 100644
--- a/source/blender/windowmanager/intern/wm_window.c
+++ b/source/blender/windowmanager/intern/wm_window.c
@@ -68,7 +68,6 @@
 #include "wm.h"
 #include "wm_draw.h"
 #include "wm_window.h"
-#include "wm_subwindow.h"
 #include "wm_event_system.h"
 
 #include "ED_scene.h"
@@ -215,7 +214,6 @@ void wm_window_free(bContext *C, wmWindowManager *wm, wmWindow *win)
 	if (win->eventstate) MEM_freeN(win->eventstate);
 	
 	wm_event_free_all(win);
-	wm_subwindows_free(win);
 
 	wm_draw_data_free(win);
 
diff --git a/source/blender/windowmanager/wm_subwindow.h b/source/blender/windowmanager/wm_subwindow.h
deleted file mode 100644
index 77c44d763f7..00000000000
--- a/source/blender/windowmanager/wm_subwindow.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * ***** BEGIN GPL LICENSE BLOCK *****
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version. 
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2007 Blender Foundation.
- * All rights reserved.
- *
- * 
- * Contributor(s): Blender Foundation
- *
- * ***** END GPL LICENSE BLOCK *****
- */
-
-/** \file blender/windowmanager/wm_subwindow.h
- *  \ingroup wm
- */
-
-
-#ifndef __WM_SUBWINDOW_H__
-#define __WM_SUBWINDOW_H__
-
-
-/* *************** internal api ************** */
-void	wm_subwindows_free(wmWindow *win);
-
-int		wm_subwindow_open(wmWindow *win, const rcti *winrct, bool activate);
-void	wm_subwindow_close(wmWindow *win, int swinid);
-
-void	wm_subwindow_position(wmWindow *win, int swinid, const rcti *winrct, bool activate);
-
-void	wm_subwindow_size_get(wmWindow *win, int swinid, int *x, int *y);
-void	wm_subwindow_origin_get(wmWindow *win, int swinid, int *x, int *y);
-void	wm_subwindow_matrix_get(wmWindow *win, int swinid, float mat[4][4]);
-void	wm_subwindow_rect_get(wmWindow *win, int swinid, struct rcti *r_rect);
-void    wm_subwindow_rect_set(wmWindow *win, int swinid, const rcti *rect);
-
-#endif /* __WM_SUBWINDOW_H__ */
-