Grease Pencil: UI (i.e. Panel) for Settings

Restored the UI for access to the GP layers. 

There are still a few minor bugs here:
* Wrong icons on the toggles - even when they're enabled, they only show a single state
* The ID-template doesn't seem to be showing up. Dunno what's going wrong there...

5 files changed, 279 insertions, 201 deletions

diff --git a/source/blender/editors/gpencil/gpencil_buttons.c b/source/blender/editors/gpencil/gpencil_buttons.c
index 12e987af47b..b572cd6916a 100644
--- a/source/blender/editors/gpencil/gpencil_buttons.c
+++ b/source/blender/editors/gpencil/gpencil_buttons.c
@@ -47,11 +47,11 @@
 #include "BKE_gpencil.h"
 #include "BKE_utildefines.h"
 
-#include "PIL_time.h"
-
 #include "WM_api.h"
 #include "WM_types.h"
 
+#include "RNA_access.h"
+
 #include "BIF_gl.h"
 #include "BIF_glutil.h"
 
@@ -76,259 +76,195 @@
 /* ------- Callbacks ----------- */
 /* These are just 'dummy wrappers' around gpencil api calls */
 
-#if 0
-// XXX
-/* make layer active one after being clicked on */
-void gp_ui_activelayer_cb (void *gpd, void *gpl)
-{
-	gpencil_layer_setactive(gpd, gpl);
-	
-	scrarea_queue_winredraw(curarea);
-	allqueue(REDRAWACTION, 0);
-}
 
-/* rename layer and set active */
-void gp_ui_renamelayer_cb (void *gpd_arg, void *gpl_arg)
+/* make layer active one after being clicked on */
+void gp_ui_activelayer_cb (bContext *C, void *gpd, void *gpl)
 {
-	bGPdata *gpd= (bGPdata *)gpd_arg;
-	bGPDlayer *gpl= (bGPDlayer *)gpl_arg;
-	
-	BLI_uniquename(&gpd->layers, gpl, "GP_Layer", '.', offsetof(bGPDlayer, info[0]), 128);
 	gpencil_layer_setactive(gpd, gpl);
 	
-	scrarea_queue_winredraw(curarea);
-	allqueue(REDRAWACTION, 0);
-}
-
-/* add a new layer */
-void gp_ui_addlayer_cb (void *gpd, void *dummy)
-{
-	gpencil_layer_addnew(gpd);
-	
-	scrarea_queue_winredraw(curarea);
-	allqueue(REDRAWACTION, 0);
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
 }
 
-/* delete active layer */
-void gp_ui_dellayer_cb (void *gpd, void *dummy)
+/* delete 'active' layer */
+void gp_ui_dellayer_cb (bContext *C, void *gpd, void *gpl)
 {
+	/* make sure the layer we want to remove is the active one */
+	gpencil_layer_setactive(gpd, gpl); 
 	gpencil_layer_delactive(gpd);
 	
-	scrarea_queue_winredraw(curarea);
-	allqueue(REDRAWACTION, 0);
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
 }
 
-/* delete last stroke of active layer */
-void gp_ui_delstroke_cb (void *gpd, void *gpl)
-{
-	bGPDframe *gpf= gpencil_layer_getframe(gpl, CFRA, 0);
-	
-	if (gpf) {
-		if (gpf->framenum != CFRA) return;
-
-		gpencil_layer_setactive(gpd, gpl);
-		gpencil_frame_delete_laststroke(gpl, gpf);
-		
-		scrarea_queue_winredraw(curarea);
-	}
-}
-
-/* delete active frame of active layer */
-void gp_ui_delframe_cb (void *gpd, void *gpl)
-{
-	bGPDframe *gpf= gpencil_layer_getframe(gpl, CFRA, 0);
-	
-	gpencil_layer_setactive(gpd, gpl);
-	gpencil_layer_delframe(gpl, gpf);
-	
-	scrarea_queue_winredraw(curarea);
-	allqueue(REDRAWACTION, 0);
-}
-
-/* convert the active layer to geometry */
-void gp_ui_convertlayer_cb (void *gpd, void *gpl)
-{
-	gpencil_layer_setactive(gpd, gpl);
-	gpencil_convert_menu();
-	
-	scrarea_queue_winredraw(curarea);
-}
-#endif
-
 /* ------- Drawing Code ------- */
 
-#if 0
-/* XXX */
 /* draw the controls for a given layer */
-static void gp_drawui_layer (uiBlock *block, bGPdata *gpd, bGPDlayer *gpl, short *xco, short *yco)
+static void gp_drawui_layer (uiLayout *layout, bGPdata *gpd, bGPDlayer *gpl)
 {
+	uiLayout *box=NULL, *split=NULL;
+	uiLayout *col=NULL, *subcol=NULL;
+	uiLayout *row=NULL, *subrow=NULL;
+	uiBlock *block;
 	uiBut *but;
-	short active= (gpl->flag & GP_LAYER_ACTIVE);
-	short width= 314;
-	short height;
-	int rb_col;
+	PointerRNA ptr;
+	
+	/* make pointer to layer data */
+	RNA_pointer_create((ID *)gpd, &RNA_GPencilLayer, gpl, &ptr);
 	
 	/* unless button has own callback, it adds this callback to button */
+	block= uiLayoutGetBlock(layout);
 	uiBlockSetFunc(block, gp_ui_activelayer_cb, gpd, gpl);
 	
-	/* draw header */
-	{
-		uiBlockSetEmboss(block, UI_EMBOSSN);
-		
-		/* rounded header */
-		if (active) uiBlockSetCol(block, TH_BUT_ACTION);
-			rb_col= (active)?-20:20;
-			uiDefBut(block, ROUNDBOX, B_REDR, "", *xco-8, *yco-2, width, 24, NULL, 5.0, 0.0, 15.0, (float)(rb_col-20), ""); 
-		if (active) uiBlockSetCol(block, TH_AUTO);
-		
-		/* lock toggle */
-		uiDefIconButBitI(block, ICONTOG, GP_LAYER_LOCKED, B_REDR, ICON_UNLOCKED,	*xco-7, *yco-1, 20, 20, &gpl->flag, 0.0, 0.0, 0, 0, "Layer cannot be modified");
-	}
+	/* draw header ---------------------------------- */
+	/* get layout-row + UI-block for header */
+	box= uiLayoutBox(layout);
+	
+	row= uiLayoutRow(box, 0);
+	block= uiLayoutGetBlock(row); // err...
+	
+	uiBlockSetEmboss(block, UI_EMBOSSN);
+	
+	/* left-align ............................... */
+	subrow= uiLayoutRow(row, 1);
+	uiLayoutSetAlignment(subrow, UI_LAYOUT_ALIGN_LEFT);
+	
+	/* active */
+	uiItemR(subrow, "", ICON_RADIOBUT_OFF, &ptr, "active", UI_ITEM_R_TOGGLE); // XXX we need to set it to toggle to get icon
+	
+	/* locked */
+	uiItemR(subrow, "", ICON_UNLOCKED, &ptr, "locked", UI_ITEM_R_TOGGLE); // XXX we need to set it to toggle to get icon
 	
 	/* when layer is locked or hidden, only draw header */
 	if (gpl->flag & (GP_LAYER_LOCKED|GP_LAYER_HIDE)) {
 		char name[256]; /* gpl->info is 128, but we need space for 'locked/hidden' as well */
 		
-		height= 0;
-		
 		/* visibility button (only if hidden but not locked!) */
 		if ((gpl->flag & GP_LAYER_HIDE) && !(gpl->flag & GP_LAYER_LOCKED))
-			uiDefIconButBitI(block, ICONTOG, GP_LAYER_HIDE, B_REDR, ICON_RESTRICT_VIEW_OFF,	*xco+12, *yco-1, 20, 20, &gpl->flag, 0.0, 0.0, 0, 0, "Visibility of layer");
+			uiItemR(subrow, "", ICON_RESTRICT_VIEW_OFF, &ptr, "hide", UI_ITEM_R_TOGGLE); // XXX we need to set it to toggle to get icon
 		
 		/* name */
 		if (gpl->flag & GP_LAYER_HIDE)
 			sprintf(name, "%s (Hidden)", gpl->info);
 		else
 			sprintf(name, "%s (Locked)", gpl->info);
-		uiDefBut(block, LABEL, 1, name,	*xco+35, *yco, 240, 20, NULL, 0.0, 0.0, 0, 0, "Short description of what this layer is for (optional)");
+		uiItemL(subrow, name, 0);
 			
 		/* delete button (only if hidden but not locked!) */
 		if ((gpl->flag & GP_LAYER_HIDE) & !(gpl->flag & GP_LAYER_LOCKED)) {
-			but= uiDefIconBut(block, BUT, B_REDR, ICON_X, *xco+(width-30), *yco, 19, 19, NULL, 0.0, 0.0, 0.0, 0.0, "Delete layer");
-			uiButSetFunc(but, gp_ui_dellayer_cb, gpd, NULL);
+			/* right-align ............................... */
+			subrow= uiLayoutRow(row, 1);
+			uiLayoutSetAlignment(subrow, UI_LAYOUT_ALIGN_RIGHT);
+			block= uiLayoutGetBlock(subrow); // XXX... err...
+			
+			but= uiDefIconBut(block, BUT, 0, ICON_X, 0, 0, UI_UNIT_X, UI_UNIT_Y, NULL, 0.0, 0.0, 0.0, 0.0, "Delete layer");
+			uiButSetFunc(but, gp_ui_dellayer_cb, gpd, gpl);
 		}	
 		uiBlockSetEmboss(block, UI_EMBOSS);
 	}
 	else {
-		height= 97;
+		/* draw rest of header -------------------------------- */
+		/* visibility button */
+		uiItemR(subrow, "", ICON_RESTRICT_VIEW_OFF, &ptr, "hide", UI_ITEM_R_TOGGLE); // XXX we need to set it to toggle to get icon
 		
-		/* draw rest of header */
-		{
-			/* visibility button */
-			uiDefIconButBitI(block, ICONTOG, GP_LAYER_HIDE, B_REDR, ICON_RESTRICT_VIEW_OFF,	*xco+12, *yco-1, 20, 20, &gpl->flag, 0.0, 0.0, 0, 0, "Visibility of layer");
-			
-			uiBlockSetEmboss(block, UI_EMBOSS);
-			
-			/* name */
-			but= uiDefButC(block, TEX, B_REDR, "Info:",	*xco+36, *yco, 240, 19, gpl->info, 0, 127, 0, 0, "Short description of what this layer is for (optional)");
-			uiButSetFunc(but, gp_ui_renamelayer_cb, gpd, gpl);
-			
-			/* delete 'button' */
-			uiBlockSetEmboss(block, UI_EMBOSSN);
-			
-			but= uiDefIconBut(block, BUT, B_REDR, ICON_X, *xco+(width-30), *yco, 19, 19, NULL, 0.0, 0.0, 0.0, 0.0, "Delete layer");
-			uiButSetFunc(but, gp_ui_dellayer_cb, gpd, NULL);
-			
-			uiBlockSetEmboss(block, UI_EMBOSS);
-		}
+		uiBlockSetEmboss(block, UI_EMBOSS);
 		
-		/* draw backdrop */
-		if (active) uiBlockSetCol(block, TH_BUT_ACTION);
-			uiDefBut(block, ROUNDBOX, B_DIFF, "", *xco-8, *yco-height, width, height-1, NULL, 5.0, 0.0, 12.0, (float)rb_col, ""); 
-		if (active) uiBlockSetCol(block, TH_AUTO);
+		/* name */
+		uiItemR(subrow, "", 0, &ptr, "info", 0);
 		
-		/* draw settings */
-		{
-			/* color */
-			uiBlockBeginAlign(block);
-				uiDefButF(block, COL, B_REDR, "",		*xco, *yco-26, 150, 19, gpl->color, 0, 0, 0, 0, "Color to use for all strokes on this Grease Pencil Layer");
-				uiDefButF(block, NUMSLI, B_REDR, "Opacity: ",		*xco,*yco-45,150,19, &gpl->color[3], 0.3f, 1.0f, 0, 0, "Visibility of stroke (0.3 to 1.0)");
-			uiBlockEndAlign(block);
-			
-			/* stroke thickness */
-			uiDefButS(block, NUMSLI, B_REDR, "Thickness:",	*xco, *yco-75, 150, 20, &gpl->thickness, 1, 10, 0, 0, "Thickness of strokes (in pixels)");
-			
-			/* debugging options */
-			if (G.f & G_DEBUG) {
-				uiDefButBitI(block, TOG, GP_LAYER_DRAWDEBUG, B_REDR, "Show Points", *xco, *yco-95, 150, 20, &gpl->flag, 0, 0, 0, 0, "Show points which form the strokes");
-			}
+		/* delete 'button' */
+		uiBlockSetEmboss(block, UI_EMBOSSN);
+			/* right-align ............................... */
+			subrow= uiLayoutRow(row, 1);
+			uiLayoutSetAlignment(subrow, UI_LAYOUT_ALIGN_RIGHT);
+			block= uiLayoutGetBlock(subrow); // XXX... err...
 			
-			/* onion-skinning */
-			uiBlockBeginAlign(block);
-				uiDefButBitI(block, TOG, GP_LAYER_ONIONSKIN, B_REDR, "Onion-Skin", *xco+160, *yco-26, 140, 20, &gpl->flag, 0, 0, 0, 0, "Ghost frames on either side of frame");
-				uiDefButS(block, NUMSLI, B_REDR, "GStep:",	*xco+160, *yco-46, 140, 20, &gpl->gstep, 0, 120, 0, 0, "Max number of frames on either side of active frame to show (0 = just 'first' available sketch on either side)");
-			uiBlockEndAlign(block);
+			but= uiDefIconBut(block, BUT, 0, ICON_X, 0, 0, UI_UNIT_X, UI_UNIT_Y, NULL, 0.0, 0.0, 0.0, 0.0, "Delete layer");
+			uiButSetFunc(but, gp_ui_dellayer_cb, gpd, gpl);
+		uiBlockSetEmboss(block, UI_EMBOSS);
+		
+		
+		/* new backdrop ----------------------------------- */
+		box= uiLayoutBox(layout);
+		split= uiLayoutSplit(box, 0.5f);
+		
+		
+		/* draw settings ---------------------------------- */
+		/* left column ..................... */
+		col= uiLayoutColumn(split, 0);
+		
+		/* color */
+		subcol= uiLayoutColumn(col, 1);
+			uiItemR(subcol, "", 0, &ptr, "color", 0);
+			uiItemR(subcol, NULL, 0, &ptr, "opacity", UI_ITEM_R_SLIDER);
 			
-			/* options */
-			uiBlockBeginAlign(block);
-				if (curarea->spacetype == SPACE_VIEW3D) {
-					but= uiDefBut(block, BUT, B_REDR, "Convert to...", *xco+160, *yco-75, 140, 20, NULL, 0, 0, 0, 0, "Converts this layer's strokes to geometry (Hotkey = Alt-Shift-C)");
-					uiButSetFunc(but, gp_ui_convertlayer_cb, gpd, gpl);
-				}
-				else {
-					but= uiDefBut(block, BUT, B_REDR, "Del Active Frame", *xco+160, *yco-75, 140, 20, NULL, 0, 0, 0, 0, "Erases the the active frame for this layer (Hotkey = Alt-XKEY/DEL)");
-					uiButSetFunc(but, gp_ui_delframe_cb, gpd, gpl);
-				}
-				
-				but= uiDefBut(block, BUT, B_REDR, "Del Last Stroke", *xco+160, *yco-95, 140, 20, NULL, 0, 0, 0, 0, "Erases the last stroke from the active frame (Hotkey = Alt-XKEY/DEL)");
-				uiButSetFunc(but, gp_ui_delstroke_cb, gpd, gpl);
-			uiBlockEndAlign(block);
+		/* stroke thickness */
+		subcol= uiLayoutColumn(col, 1);
+			uiItemR(subcol, NULL, 0, &ptr, "line_thickness", UI_ITEM_R_SLIDER);
+		
+		/* debugging options */
+		if (G.f & G_DEBUG) {
+			// XXX this option hasn't been wrapped yet... since it's just debug
+			//subcol= uiLayoutColumn(col, 1);
+			//	uiItemR(subrow, NULL, 0, &ptr, "show_points", 0);
 		}
+		
+		/* right column ................... */
+		col= uiLayoutColumn(split, 0);
+		
+		/* onion-skinning */
+		subcol= uiLayoutColumn(col, 1);
+			uiItemR(subcol, "Onion Skinning", 0, &ptr, "use_onion_skinning", 0);
+			uiItemR(subcol, "GStep", 0, &ptr, "max_ghost_range", 0); // XXX shorter name here? (i.e. GStep)
+		
+		/* additional options... */
+		// None at the moment...
 	}
-	
-	/* adjust height for new to start */
-	(*yco) -= (height + 27); 
 } 
-#endif
-/* Draw the contents for a grease-pencil panel. This assumes several things:
- * 	- that panel has been created, is 318 x 204. max yco is 225
- *	- that a toggle for turning on/off gpencil drawing is 150 x 20, starting from (10,225)
- *		which is basically the top left-hand corner
- * It will return the amount of extra space to extend the panel by
- */
-short draw_gpencil_panel (uiBlock *block, bGPdata *gpd, ScrArea *sa)
+
+/* Draw the contents for a grease-pencil panel*/
+static void draw_gpencil_panel (bContext *C, uiLayout *layout, bGPdata *gpd, PointerRNA *ctx_ptr)
 {
-#if 0
-	uiBut *but;
 	bGPDlayer *gpl;
-	short xco= 10, yco= 170;
+	uiLayout *col;
 	
-	/* draw gpd settings first */
-	{
-		/* add new layer buttons */
-		but= uiDefBut(block, BUT, B_REDR, "Add New Layer", 10,205,150,20, 0, 0, 0, 0, 0, "Adds a new Grease Pencil Layer");
-		uiButSetFunc(but, gp_ui_addlayer_cb, gpd, NULL);
+	/* draw gpd settings first ------------------------------------- */
+	col= uiLayoutColumn(layout, 1);
+		/* current Grease Pencil block */
+		// TODO: show some info about who owns this?
+			// XXX: this template doesn't show up!
+		uiTemplateID(col, C, ctx_ptr, "grease_pencil", "GPENCIL_OT_data_new", "GPENCIL_OT_data_unlink");
 		
-		
-		/* show override lmb-clicks button + painting lock */
-		uiBlockBeginAlign(block);
-			if ((gpd->flag & GP_DATA_EDITPAINT)==0) {
-				uiDefButBitI(block, TOG, GP_DATA_EDITPAINT, B_REDR, "Draw Mode", 170, 225, 130, 20, &gpd->flag, 0, 0, 0, 0, "Interpret click-drag as new strokes");
-				
-				uiBlockSetCol(block, TH_BUT_SETTING);
-					uiDefIconButBitI(block, ICONTOG, GP_DATA_LMBPLOCK, B_REDR, ICON_UNLOCKED,	300, 225, 20, 20, &gpd->flag, 0.0, 0.0, 0, 0, "Painting cannot occur with Shift-LMB (when making selections)");
-				uiBlockSetCol(block, TH_AUTO);
-			}
-			else
-				uiDefButBitI(block, TOG, GP_DATA_EDITPAINT, B_REDR, "Draw Mode", 170, 225, 150, 20, &gpd->flag, 0, 0, 0, 0, "Interpret click-drag as new strokes");
-		uiBlockEndAlign(block);
-		
-		/* 'view align' button (naming depends on context) */
-		if (sa->spacetype == SPACE_VIEW3D)
-			uiDefButBitI(block, TOG, GP_DATA_VIEWALIGN, B_REDR, "Sketch in 3D", 170, 205, 150, 20, &gpd->flag, 0, 0, 0, 0, "New strokes are added in 3D-space");
-		else
-			uiDefButBitI(block, TOG, GP_DATA_VIEWALIGN, B_REDR, "Stick to View", 170, 205, 150, 20, &gpd->flag, 0, 0, 0, 0, "New strokes are added on 2d-canvas");
-	}
+		/* add new layer button */
+		uiItemO(col, NULL, 0, "GPENCIL_OT_layer_add");
 	
-	/* draw for each layer */
+	/* 'view align' button (naming depends on context) */
+#if 0 // XXX for now, this is enabled by default anyways
+	if (sa->spacetype == SPACE_VIEW3D)
+		uiDefButBitI(block, TOG, GP_DATA_VIEWALIGN, B_REDR, "Sketch in 3D", 170, 205, 150, 20, &gpd->flag, 0, 0, 0, 0, "New strokes are added in 3D-space");
+	else
+		uiDefButBitI(block, TOG, GP_DATA_VIEWALIGN, B_REDR, "Stick to View", 170, 205, 150, 20, &gpd->flag, 0, 0, 0, 0, "New strokes are added on 2d-canvas");
+#endif
+	
+	/* draw each layer --------------------------------------------- */
 	for (gpl= gpd->layers.first; gpl; gpl= gpl->next) {
-		gp_drawui_layer(block, gpd, gpl, &xco, &yco);
+		col= uiLayoutColumn(layout, 1);
+			gp_drawui_layer(col, gpd, gpl);
 	}
-	
-	/* return new height if necessary */
-	return (yco < 0) ? (204 - yco) : 204;
-#endif
-	return 0;
 }	
 
+
+/* Standard panel to be included whereever Grease Pencil is used... */
+void gpencil_panel_standard(const bContext *C, Panel *pa)
+{
+	bGPdata **gpd_ptr = NULL;
+	PointerRNA ptr;
+	
+	//if (v3d->flag2 & V3D_DISPGP)... etc.
+	
+	/* get pointer to Grease Pencil Data */
+	gpd_ptr= gpencil_data_get_pointers((bContext *)C, &ptr);
+	
+	if (gpd_ptr && *gpd_ptr)
+		draw_gpencil_panel((bContext *)C, pa->layout, *gpd_ptr, &ptr);
+}
+
 /* ************************************************** */
diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil/gpencil_edit.c
index 3130e190ce2..2faf3ccbbda 100644
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil/gpencil_edit.c
@@ -60,6 +60,7 @@
 #include "BKE_gpencil.h"
 #include "BKE_image.h"
 #include "BKE_library.h"
+#include "BKE_report.h"
 #include "BKE_utildefines.h"
 
 #include "BIF_gl.h"
@@ -123,6 +124,9 @@ bGPdata **gpencil_data_get_pointers (bContext *C, PointerRNA *ptr)
 				/* return the GP data for the active strips/image/etc. */
 			}
 				break;
+				
+			default: /* unsupported space */
+				return NULL;
 		}
 	}
 	
@@ -141,6 +145,128 @@ bGPdata *gpencil_data_get_active (bContext *C)
 /* ************************************************ */
 /* Panel Operators */
 
+/* poll callback for adding data/layers - special */
+static int gp_add_poll (bContext *C)
+{
+	/* the base line we have is that we have somewhere to add Grease Pencil data */
+	return gpencil_data_get_pointers(C, NULL) != NULL;
+}
+
+/* ******************* Add New Data ************************ */
+
+/* add new datablock - wrapper around API */
+static int gp_data_add_exec (bContext *C, wmOperator *op)
+{
+	bGPdata **gpd_ptr= gpencil_data_get_pointers(C, NULL);
+	
+	if (gpd_ptr == NULL) {
+		BKE_report(op->reports, RPT_ERROR, "Nowhere for Grease Pencil data to go");
+		return OPERATOR_CANCELLED;
+	}
+	else {
+		/* just add new datablock now */
+		*gpd_ptr= gpencil_data_addnew("GPencil");
+	}
+	
+	/* notifiers */
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
+	
+	return OPERATOR_FINISHED;
+}
 
+void GPENCIL_OT_data_add (wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name= "Grease Pencil Add New";
+	ot->idname= "GPENCIL_OT_data_add";
+	ot->description= "Add new Grease Pencil datablock.";
+	
+	/* callbacks */
+	ot->exec= gp_data_add_exec;
+	ot->poll= gp_add_poll;
+}
+
+/* ******************* Unlink Data ************************ */
+
+/* poll callback for adding data/layers - special */
+static int gp_data_unlink_poll (bContext *C)
+{
+	bGPdata **gpd_ptr= gpencil_data_get_pointers(C, NULL);
+	
+	/* if we have access to some active data, make sure there's a datablock before enabling this */
+	return (gpd_ptr && *gpd_ptr);
+}
+
+
+/* unlink datablock - wrapper around API */
+static int gp_data_unlink_exec (bContext *C, wmOperator *op)
+{
+	bGPdata **gpd_ptr= gpencil_data_get_pointers(C, NULL);
+	
+	if (gpd_ptr == NULL) {
+		BKE_report(op->reports, RPT_ERROR, "Nowhere for Grease Pencil data to go");
+		return OPERATOR_CANCELLED;
+	}
+	else {
+		/* just unlink datablock now, decreasing its user count */
+		bGPdata *gpd= (*gpd_ptr);
+		
+		gpd->id.us--;
+		*gpd_ptr= NULL;
+	}
+	
+	/* notifiers */
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
+	
+	return OPERATOR_FINISHED;
+}
+
+void GPENCIL_OT_data_unlink (wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name= "Grease Pencil Unlink";
+	ot->idname= "GPENCIL_OT_data_unlink";
+	ot->description= "Unlink active Grease Pencil datablock.";
+	
+	/* callbacks */
+	ot->exec= gp_data_unlink_exec;
+	ot->poll= gp_data_unlink_poll;
+}
+
+/* ******************* Add New Layer ************************ */
+
+/* add new layer - wrapper around API */
+static int gp_layer_add_exec (bContext *C, wmOperator *op)
+{
+	bGPdata **gpd_ptr= gpencil_data_get_pointers(C, NULL);
+	
+	/* if there's no existing Grease-Pencil data there, add some */
+	if (gpd_ptr == NULL) {
+		BKE_report(op->reports, RPT_ERROR, "Nowhere for Grease Pencil data to go");
+		return OPERATOR_CANCELLED;
+	}
+	if (*gpd_ptr == NULL)
+		*gpd_ptr= gpencil_data_addnew("GPencil");
+		
+	/* add new layer now */
+	gpencil_layer_addnew(*gpd_ptr);
+	
+	/* notifiers */
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
+	
+	return OPERATOR_FINISHED;
+}
+
+void GPENCIL_OT_layer_add (wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name= "Add New Layer";
+	ot->idname= "GPENCIL_OT_layer_add";
+	ot->description= "Add new Grease Pencil layer for the active Grease Pencil datablock.";
+	
+	/* callbacks */
+	ot->exec= gp_layer_add_exec;
+	ot->poll= gp_add_poll;
+}
 
 /* ************************************************ */
diff --git a/source/blender/editors/gpencil/gpencil_intern.h b/source/blender/editors/gpencil/gpencil_intern.h
index b134328c8a0..cc98d491f7a 100644
--- a/source/blender/editors/gpencil/gpencil_intern.h
+++ b/source/blender/editors/gpencil/gpencil_intern.h
@@ -40,6 +40,13 @@ struct wmOperatorType;
 
 void GPENCIL_OT_draw(struct wmOperatorType *ot);
 
+/* buttons editing --- */
+
+void GPENCIL_OT_data_add(struct wmOperatorType *ot);
+void GPENCIL_OT_data_unlink(struct wmOperatorType *ot);
+
+void GPENCIL_OT_layer_add(struct wmOperatorType *ot);
+
 
 /******************************************************* */
 /* FILTERED ACTION DATA - TYPES  ---> XXX DEPRECEATED OLD ANIM SYSTEM CODE! */
diff --git a/source/blender/editors/gpencil/gpencil_ops.c b/source/blender/editors/gpencil/gpencil_ops.c
index 347a611ee30..364b27b61b0 100644
--- a/source/blender/editors/gpencil/gpencil_ops.c
+++ b/source/blender/editors/gpencil/gpencil_ops.c
@@ -66,10 +66,16 @@ void gpencil_common_keymap(wmWindowManager *wm, ListBase *keymap)
 void ED_operatortypes_gpencil (void)
 {
 	/* Drawing ----------------------- */
+	
 	WM_operatortype_append(GPENCIL_OT_draw);
 	
 	/* Editing (Buttons) ------------ */
 	
+	WM_operatortype_append(GPENCIL_OT_data_add);
+	WM_operatortype_append(GPENCIL_OT_data_unlink);
+	
+	WM_operatortype_append(GPENCIL_OT_layer_add);
+	
 	/* Editing (Time) --------------- */
 }
 
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index 445d9ae346d..82dc76a2152 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -919,7 +919,7 @@ static void gp_paint_initstroke (tGPsdata *p, short paintmode)
 				View3D *v3d= (View3D *)p->sa->spacedata.first;
 				RegionView3D *rv3d= p->ar->regiondata;
 				
-				// TODO: this should only happen for scene... otherwise use object center!
+				// TODO: this should only happen for scene... otherwise apply correction for object center!
 				float *fp= give_cursor(p->scene, v3d);
 				initgrabz(rv3d, fp[0], fp[1], fp[2]);
 				
@@ -1231,6 +1231,9 @@ static int gpencil_draw_exec (bContext *C, wmOperator *op)
 	/* cleanup */
 	gpencil_draw_exit(C, op);
 	
+	/* refreshes */
+	WM_event_add_notifier(C, NC_SCREEN|ND_GPENCIL|NA_EDITED, NULL); // XXX please work!
+	
 	/* done */
 	return OPERATOR_FINISHED;
 }