UI: New Global Top-Bar (WIP)

== Main Features/Changes for Users

* Add horizontal bar at top of all non-temp windows, consisting out of two horizontal sub-bars.
* Upper sub-bar contains global menus (File, Render, etc.), tabs for workspaces and scene selector.
* Lower sub-bar contains object mode selector, screen-layout and render-layer selector. Later operator and/or tool settings will be placed here.
* Individual sections of the topbar are individually scrollable.
* Workspace tabs can be double- or ctrl-clicked for renaming and contain 'x' icon for deleting.
* Top-bar should scale nicely with DPI.
* The lower half of the top-bar can be hided by dragging the lower top-bar edge up. Better hiding options are planned (e.g. hide in fullscreen modes).
* Info editors at the top of the window and using the full window width with be replaced by the top-bar.
* In fullscreen modes, no more info editor is added on top, the top-bar replaces it.

== Technical Features/Changes

* Adds initial support for global areas

  A global area is part of the window, not part of the regular screen-layout.
  I've added a macro iterator to iterate over both, global and screen-layout level areas. When iterating over areas, from now on developers should always consider if they have to include global areas.
* Adds a TOPBAR editor type

  The editor type is hidden in the UI editor type menu.
* Adds a variation of the ID template to display IDs as tab buttons (template_ID_tabs in BPY)
* Does various changes to RNA button creation code to improve their appearance in the horizontal top-bar.
* Adds support for dynamically sized regions. That is, regions that scale automatically to the layout bounds.

  The code for this is currently a big hack (it's based on drawing the UI multiple times). This should definitely be improved.
* Adds a template for displaying operator properties optimized for the top-bar. This will probably change a lot still and is in fact disabled in code.

Since the final top-bar design depends a lot on other 2.8 designs (mainly tool-system and workspaces), we decided to not show the operator or tool settings in the top-bar for now. That means most of the lower sub-bar is empty for the time being.

NOTE: Top-bar or global area data is not written to files or SDNA. They are simply added to the window when opening Blender or reading a file. This allows us doing changes to the top-bar without having to care for compatibility.

== ToDo's

It's a bit hard to predict all the ToDo's here are the known main ones:
* Add options for the new active-tool system and for operator redo to the topbar.
* Automatically hide the top-bar in fullscreen modes.
* General visual polish.
* Top-bar drag & drop support (WIP in temp-tab_drag_drop).
* Improve dynamic regions (should also fix some layout glitches).
* Make internal terminology consistent.
* Enable topbar file writing once design is more advanced.
* Address TODO's and XXX's in code :)

Thanks @brecht for the review! And @sergey for the complaining ;)

Differential Revision: D2758

7 files changed, 516 insertions, 208 deletions

diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 105fff38f62..b6e2d2c57d4 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -1168,7 +1168,7 @@ static bool region_is_overlap(wmWindow *win, ScrArea *sa, ARegion *ar)
 	return 0;
 }
 
-static void region_rect_recursive(wmWindow *win, ScrArea *sa, ARegion *ar, rcti *remainder, int quad)
+static void region_rect_recursive(wmWindow *win, ScrArea *sa, ARegion *ar, rcti *remainder, int quad, bool add_azones)
 {
 	rcti *remainder_prev = remainder;
 	int prefsizex, prefsizey;
@@ -1195,13 +1195,17 @@ static void region_rect_recursive(wmWindow *win, ScrArea *sa, ARegion *ar, rcti
 	/* user errors */
 	if (ar->next == NULL && alignment != RGN_ALIGN_QSPLIT)
 		alignment = RGN_ALIGN_NONE;
-	
+
 	/* prefsize, for header we stick to exception (prevent dpi rounding error) */
-	prefsizex = UI_DPI_FAC * (ar->sizex > 1 ? ar->sizex + 0.5f : ar->type->prefsizex);
-	
+	const float sizex_dpi_fac = (ar->flag & RGN_SIZEX_DPI_APPLIED) ? 1.0f : UI_DPI_FAC;
+	prefsizex = sizex_dpi_fac * ((ar->sizex > 1) ? ar->sizex + 0.5f : ar->type->prefsizex);
+
 	if (ar->regiontype == RGN_TYPE_HEADER) {
 		prefsizey = ED_area_headersize();
 	}
+	else if (ED_area_is_global(sa)) {
+		prefsizey = ED_region_global_size_y();
+	}
 	else if (ar->regiontype == RGN_TYPE_UI && sa->spacetype == SPACE_FILE) {
 		prefsizey = UI_UNIT_Y * 2 + (UI_UNIT_Y / 2);
 	}
@@ -1397,7 +1401,7 @@ static void region_rect_recursive(wmWindow *win, ScrArea *sa, ARegion *ar, rcti
 		 * but accounts for small common rounding problems when scaling the UI,
 		 * must be minimum '4' */
 	}
-	else {
+	else if (add_azones) {
 		const bScreen *screen = WM_window_get_active_screen(win);
 
 		if (ELEM(screen->state, SCREENNORMAL, SCREENMAXIMIZED)) {
@@ -1409,23 +1413,36 @@ static void region_rect_recursive(wmWindow *win, ScrArea *sa, ARegion *ar, rcti
 		}
 	}
 
-	region_rect_recursive(win, sa, ar->next, remainder, quad);
+	region_rect_recursive(win, sa, ar->next, remainder, quad, add_azones);
 }
 
-static void area_calc_totrct(ScrArea *sa, int sizex, int sizey)
+static void area_calc_totrct(ScrArea *sa, int window_size_x, int window_size_y)
 {
-	short rt = (short) U.pixelsize;
+	short px = (short)U.pixelsize;
+
+	sa->totrct.xmin = sa->v1->vec.x;
+	sa->totrct.xmax = sa->v4->vec.x;
+	sa->totrct.ymin = sa->v1->vec.y;
+	sa->totrct.ymax = sa->v2->vec.y;
+
+	/* scale down totrct by 1 pixel on all sides not matching window borders */
+	if (sa->totrct.xmin > 0) {
+		sa->totrct.xmin += px;
+	}
+	if (sa->totrct.xmax < (window_size_x - 1)) {
+		sa->totrct.xmax -= px;
+	}
+	if (sa->totrct.ymin > 0) {
+		sa->totrct.ymin += px;
+	}
+	if (sa->totrct.ymax < (window_size_y - 1)) {
+		sa->totrct.ymax -= px;
+	}
+	BLI_assert(sa->totrct.xmin >= 0);
+	BLI_assert(sa->totrct.xmax >= 0);
+	BLI_assert(sa->totrct.ymin >= 0);
+	BLI_assert(sa->totrct.ymax >= 0);
 
-	if (sa->v1->vec.x > 0) sa->totrct.xmin = sa->v1->vec.x + rt;
-	else sa->totrct.xmin = sa->v1->vec.x;
-	if (sa->v4->vec.x < sizex - 1) sa->totrct.xmax = sa->v4->vec.x - rt;
-	else sa->totrct.xmax = sa->v4->vec.x;
-	
-	if (sa->v1->vec.y > 0) sa->totrct.ymin = sa->v1->vec.y + rt;
-	else sa->totrct.ymin = sa->v1->vec.y;
-	if (sa->v2->vec.y < sizey - 1) sa->totrct.ymax = sa->v2->vec.y - rt;
-	else sa->totrct.ymax = sa->v2->vec.y;
-	
 	/* for speedup */
 	sa->winx = BLI_rcti_size_x(&sa->totrct) + 1;
 	sa->winy = BLI_rcti_size_y(&sa->totrct) + 1;
@@ -1510,11 +1527,36 @@ static void ed_default_handlers(wmWindowManager *wm, ScrArea *sa, ListBase *hand
 	}
 }
 
+void screen_area_update_region_sizes(wmWindowManager *wm, wmWindow *win, ScrArea *area)
+{
+	const int size_x = WM_window_pixels_x(win);
+	const int size_y = WM_window_pixels_y(win);
+	rcti rect;
+
+	area_calc_totrct(area, size_x, size_y);
+
+	/* region rect sizes */
+	rect = area->totrct;
+	region_rect_recursive(win, area, area->regionbase.first, &rect, 0, false);
+
+	for (ARegion *ar = area->regionbase.first; ar; ar = ar->next) {
+		region_subwindow(ar);
+
+		/* region size may have changed, init does necessary adjustments */
+		if (ar->type->init) {
+			ar->type->init(wm, ar);
+		}
+	}
+
+	area->flag &= ~AREA_FLAG_REGION_SIZE_UPDATE;
+}
 
 /* called in screen_refresh, or screens_init, also area size changes */
 void ED_area_initialize(wmWindowManager *wm, wmWindow *win, ScrArea *sa)
 {
 	const bScreen *screen = WM_window_get_active_screen(win);
+	const int window_size_x = WM_window_pixels_x(win);
+	const int window_size_y = WM_window_pixels_y(win);
 	ARegion *ar;
 	rcti rect;
 	
@@ -1528,16 +1570,17 @@ void ED_area_initialize(wmWindowManager *wm, wmWindow *win, ScrArea *sa)
 	
 	for (ar = sa->regionbase.first; ar; ar = ar->next)
 		ar->type = BKE_regiontype_from_id(sa->type, ar->regiontype);
-	
+
 	/* area sizes */
-	area_calc_totrct(sa, WM_window_pixels_x(win), WM_window_pixels_y(win));
-	
+	area_calc_totrct(sa, window_size_x, window_size_y);
+
 	/* clear all azones, add the area triange widgets */
 	area_azone_initialize(win, screen, sa);
 
 	/* region rect sizes */
 	rect = sa->totrct;
-	region_rect_recursive(win, sa, sa->regionbase.first, &rect, 0);
+	region_rect_recursive(win, sa, sa->regionbase.first, &rect, 0, true);
+	sa->flag &= ~AREA_FLAG_REGION_SIZE_UPDATE;
 	
 	/* default area handlers */
 	ed_default_handlers(wm, sa, &sa->handlers, sa->type->keymapflag);
@@ -1832,6 +1875,18 @@ int ED_area_header_switchbutton(const bContext *C, uiBlock *block, int yco)
 
 /************************ standard UI regions ************************/
 
+static ThemeColorID region_background_color_id(const bContext *C, const ARegion *region)
+{
+	switch (region->regiontype) {
+		case RGN_TYPE_HEADER:
+			return ED_screen_area_active(C) ? TH_HEADER : TH_HEADERDESEL;
+		case RGN_TYPE_PREVIEW:
+			return TH_PREVIEW_BACK;
+		default:
+			return TH_BACK;
+	}
+}
+
 void ED_region_panels(const bContext *C, ARegion *ar, const char *context, int contextnr, const bool vertical)
 {
 	const WorkSpace *workspace = CTX_wm_workspace(C);
@@ -2117,17 +2172,25 @@ void ED_region_header(const bContext *C, ARegion *ar)
 	Header header = {NULL};
 	int maxco, xco, yco;
 	int headery = ED_area_headersize();
+	const int start_ofs = 0.4f * UI_UNIT_X;
+	bool region_layout_based = ar->flag & RGN_FLAG_DYNAMIC_SIZE;
 
 	/* clear */
-	UI_ThemeClearColor((ED_screen_area_active(C)) ? TH_HEADER : TH_HEADERDESEL);
+	UI_ThemeClearColor(region_background_color_id(C, ar));
 	glClear(GL_COLOR_BUFFER_BIT);
 	
 	/* set view2d view matrix for scrolling (without scrollers) */
 	UI_view2d_view_ortho(&ar->v2d);
 
-	xco = maxco = 0.4f * UI_UNIT_X;
+	xco = maxco = start_ofs;
 	yco = headery - floor(0.2f * UI_UNIT_Y);
 
+	/* XXX workaround for 1 px alignment issue. Not sure what causes it... Would prefer a proper fix - Julian */
+	if (CTX_wm_area(C)->spacetype == SPACE_TOPBAR) {
+		xco += 1;
+		yco += 1;
+	}
+
 	/* draw all headers types */
 	for (ht = ar->type->headertypes.first; ht; ht = ht->next) {
 		block = UI_block_begin(C, ar, ht->idname, UI_EMBOSS);
@@ -2149,13 +2212,23 @@ void ED_region_header(const bContext *C, ARegion *ar)
 		/* for view2d */
 		if (xco > maxco)
 			maxco = xco;
-		
+
+		if (region_layout_based && (ar->sizex != (maxco + start_ofs))) {
+			/* region size is layout based and needs to be updated */
+			ScrArea *sa = CTX_wm_area(C);
+
+			ar->sizex = maxco + start_ofs;
+			UI_view2d_region_reinit(&ar->v2d, V2D_COMMONVIEW_HEADER, ar->sizex, ar->winy);
+
+			sa->flag |= AREA_FLAG_REGION_SIZE_UPDATE;
+			ar->flag |= RGN_SIZEX_DPI_APPLIED;
+		}
 		UI_block_end(C, block);
 		UI_block_draw(C, block);
 	}
 
 	/* always as last  */
-	UI_view2d_totRect_set(&ar->v2d, maxco + UI_UNIT_X + 80, headery);
+	UI_view2d_totRect_set(&ar->v2d, maxco + (region_layout_based ? 0 : UI_UNIT_X + 80), headery);
 
 	/* restore view matrix? */
 	UI_view2d_view_restore(C);
@@ -2172,6 +2245,31 @@ int ED_area_headersize(void)
 	return (int)(HEADERY * UI_DPI_FAC);
 }
 
+/**
+ * \return the final height of a global \a area, accounting for DPI.
+ */
+int ED_area_global_size_y(const ScrArea *area)
+{
+	BLI_assert(ED_area_is_global(area));
+	return round_fl_to_int(area->global->cur_fixed_height * UI_DPI_FAC);
+}
+
+bool ED_area_is_global(const ScrArea *area)
+{
+	return area->global != NULL;
+}
+
+/**
+ * For now we just assume all global areas are made up out of horizontal bars
+ * with the same size. A fixed size could be stored in ARegion instead if needed.
+ *
+ * \return the DPI aware height of a single bar/region in global areas.
+ */
+int ED_region_global_size_y(void)
+{
+	return ED_area_headersize(); /* same size as header */
+}
+
 void ED_region_info_draw_multiline(ARegion *ar, const char *text_array[], float fill_color[4], const bool full_redraw)
 {
 	const int header_height = UI_UNIT_Y;
diff --git a/source/blender/editors/screen/screen_edit.c b/source/blender/editors/screen/screen_edit.c
index e961a7f5d64..82093b4326a 100644
--- a/source/blender/editors/screen/screen_edit.c
+++ b/source/blender/editors/screen/screen_edit.c
@@ -76,17 +76,21 @@
 
 /* ******************* screen vert, edge, area managing *********************** */
 
-static ScrVert *screen_addvert(bScreen *sc, short x, short y)
+static ScrVert *screen_addvert_ex(ScrAreaMap *area_map, short x, short y)
 {
 	ScrVert *sv = MEM_callocN(sizeof(ScrVert), "addscrvert");
 	sv->vec.x = x;
 	sv->vec.y = y;
 	
-	BLI_addtail(&sc->vertbase, sv);
+	BLI_addtail(&area_map->vertbase, sv);
 	return sv;
 }
+static ScrVert *screen_addvert(bScreen *sc, short x, short y)
+{
+	return screen_addvert_ex(AREAMAP_FROM_SCREEN(sc), x, y);
+}
 
-static ScrEdge *screen_addedge(bScreen *sc, ScrVert *v1, ScrVert *v2)
+static ScrEdge *screen_addedge_ex(ScrAreaMap *area_map, ScrVert *v1, ScrVert *v2)
 {
 	ScrEdge *se = MEM_callocN(sizeof(ScrEdge), "addscredge");
 
@@ -94,10 +98,13 @@ static ScrEdge *screen_addedge(bScreen *sc, ScrVert *v1, ScrVert *v2)
 	se->v1 = v1;
 	se->v2 = v2;
 
-	BLI_addtail(&sc->edgebase, se);
+	BLI_addtail(&area_map->edgebase, se);
 	return se;
 }
-
+static ScrEdge *screen_addedge(bScreen *sc, ScrVert *v1, ScrVert *v2)
+{
+	return screen_addedge_ex(AREAMAP_FROM_SCREEN(sc), v1, v2);
+}
 
 bool scredge_is_horizontal(ScrEdge *se)
 {
@@ -105,16 +112,16 @@ bool scredge_is_horizontal(ScrEdge *se)
 }
 
 /* need win size to make sure not to include edges along screen edge */
-ScrEdge *screen_find_active_scredge(const bScreen *sc,
-                                    const int winsize_x, const int winsize_y,
-                                    const int mx, const int my)
+ScrEdge *screen_area_map_find_active_scredge(
+        const ScrAreaMap *area_map,
+        const int winsize_x, const int winsize_y,
+        const int mx, const int my)
 {
-	ScrEdge *se;
 	int safety = U.widget_unit / 10;
-	
-	if (safety < 2) safety = 2;
-	
-	for (se = sc->edgebase.first; se; se = se->next) {
+
+	CLAMP_MIN(safety, 2);
+
+	for (ScrEdge *se = area_map->edgebase.first; se; se = se->next) {
 		if (scredge_is_horizontal(se)) {
 			if (se->v1->vec.y > 0 && se->v1->vec.y < winsize_y - 1) {
 				short min, max;
@@ -136,27 +143,56 @@ ScrEdge *screen_find_active_scredge(const bScreen *sc,
 			}
 		}
 	}
-	
+
 	return NULL;
 }
 
+/* need win size to make sure not to include edges along screen edge */
+ScrEdge *screen_find_active_scredge(
+        const wmWindow *win, const bScreen *screen,
+        const int mx, const int my)
+{
+	/* Use layout size (screen excluding global areas) for screen-layout area edges */
+	const int screen_x = WM_window_screen_pixels_x(win), screen_y = WM_window_screen_pixels_y(win);
+	ScrEdge *se = screen_area_map_find_active_scredge(AREAMAP_FROM_SCREEN(screen), screen_x, screen_y, mx, my);
+
+	if (!se) {
+		/* Use entire window size (screen including global areas) for global area edges */
+		const int win_x = WM_window_pixels_x(win), win_y = WM_window_pixels_y(win);
+		se = screen_area_map_find_active_scredge(&win->global_areas, win_x, win_y, mx, my);
+	}
+	return se;
+}
+
 
 
 /* adds no space data */
-static ScrArea *screen_addarea(bScreen *sc, ScrVert *v1, ScrVert *v2, ScrVert *v3, ScrVert *v4, short headertype, short spacetype)
+static ScrArea *screen_addarea_ex(
+        ScrAreaMap *area_map,
+        ScrVert *bottom_left, ScrVert *top_left, ScrVert *top_right, ScrVert *bottom_right,
+        short headertype, short spacetype)
 {
 	ScrArea *sa = MEM_callocN(sizeof(ScrArea), "addscrarea");
-	sa->v1 = v1;
-	sa->v2 = v2;
-	sa->v3 = v3;
-	sa->v4 = v4;
+
+	sa->v1 = bottom_left;
+	sa->v2 = top_left;
+	sa->v3 = top_right;
+	sa->v4 = bottom_right;
 	sa->headertype = headertype;
 	sa->spacetype = sa->butspacetype = spacetype;
-	
-	BLI_addtail(&sc->areabase, sa);
-	
+
+	BLI_addtail(&area_map->areabase, sa);
+
 	return sa;
 }
+static ScrArea *screen_addarea(
+        bScreen *sc,
+        ScrVert *left_bottom, ScrVert *left_top, ScrVert *right_top, ScrVert *right_bottom,
+        short headertype, short spacetype)
+{
+	return screen_addarea_ex(AREAMAP_FROM_SCREEN(sc), left_bottom, left_top, right_top, right_bottom,
+	                         headertype, spacetype);
+}
 
 static void screen_delarea(bContext *C, bScreen *sc, ScrArea *sa)
 {
@@ -462,10 +498,10 @@ int screen_area_join(bContext *C, bScreen *scr, ScrArea *sa1, ScrArea *sa2)
 	return 1;
 }
 
-void select_connected_scredge(bScreen *sc, ScrEdge *edge)
+void select_connected_scredge(const wmWindow *win, ScrEdge *edge)
 {
+	bScreen *sc = WM_window_get_active_screen(win);
 	ScrEdge *se;
-	ScrVert *sv;
 	int oneselected;
 	char dir;
 	
@@ -475,12 +511,10 @@ void select_connected_scredge(bScreen *sc, ScrEdge *edge)
 	if (edge->v1->vec.x == edge->v2->vec.x) dir = 'v';
 	else dir = 'h';
 	
-	sv = sc->vertbase.first;
-	while (sv) {
+	ED_screen_verts_iter(win, sc, sv) {
 		sv->flag = 0;
-		sv = sv->next;
 	}
-	
+
 	edge->v1->flag = 1;
 	edge->v2->flag = 1;
 	
@@ -508,8 +542,13 @@ void select_connected_scredge(bScreen *sc, ScrEdge *edge)
 	}
 }
 
-/* test if screen vertices should be scaled */
-static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
+/**
+ * Test if screen vertices should be scaled and do if needed.
+ */
+static void screen_vertices_scale(
+        const wmWindow *win, bScreen *sc,
+        int window_size_x, int window_size_y,
+        int screen_size_x, int screen_size_y)
 {
 	/* clamp Y size of header sized areas when expanding windows
 	 * avoids annoying empty space around file menu */
@@ -518,7 +557,7 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 	const int headery_init = ED_area_headersize();
 	ScrVert *sv = NULL;
 	ScrArea *sa;
-	int winsize_x_prev, winsize_y_prev;
+	int screen_size_x_prev, screen_size_y_prev;
 	float facx, facy, tempf, min[2], max[2];
 	
 	/* calculate size */
@@ -536,8 +575,8 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 		sv->vec.y -= min[1];
 	}
 	
-	winsize_x_prev = (max[0] - min[0]) + 1;
-	winsize_y_prev = (max[1] - min[1]) + 1;
+	screen_size_x_prev = (max[0] - min[0]) + 1;
+	screen_size_y_prev = (max[1] - min[1]) + 1;
 
 
 #ifdef USE_HEADER_SIZE_CLAMP
@@ -545,14 +584,14 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 #define TEMP_TOP 2
 
 	/* if the window's Y axis grows, clamp header sized areas */
-	if (winsize_y_prev < winsize_y) {  /* growing? */
+	if (screen_size_y_prev < screen_size_y) {  /* growing? */
 		const int headery_margin_max = headery_init + 4;
 		for (sa = sc->areabase.first; sa; sa = sa->next) {
 			ARegion *ar = BKE_area_find_region_type(sa, RGN_TYPE_HEADER);
 			sa->temp = 0;
 
 			if (ar && !(ar->flag & RGN_FLAG_HIDDEN)) {
-				if (sa->v2->vec.y == winsize_y_prev - 1) {
+				if (sa->v2->vec.y == screen_size_y_prev) {
 					if ((sa->v2->vec.y - sa->v1->vec.y) < headery_margin_max) {
 						sa->temp = TEMP_TOP;
 					}
@@ -568,9 +607,9 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 #endif
 
 
-	if (winsize_x_prev != winsize_x || winsize_y_prev != winsize_y) {
-		facx = ((float)winsize_x - 1) / ((float)winsize_x_prev - 1);
-		facy = ((float)winsize_y - 1) / ((float)winsize_y_prev - 1);
+	if (screen_size_x_prev != screen_size_x || screen_size_y_prev != screen_size_y) {
+		facx = ((float)screen_size_x - 1) / ((float)screen_size_x_prev - 1);
+		facy = ((float)screen_size_y) / ((float)screen_size_y_prev);
 		
 		/* make sure it fits! */
 		for (sv = sc->vertbase.first; sv; sv = sv->next) {
@@ -581,20 +620,20 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 			//sv->vec.x += AREAGRID - 1;
 			//sv->vec.x -=  (sv->vec.x % AREAGRID);
 
-			CLAMP(sv->vec.x, 0, winsize_x - 1);
+			CLAMP(sv->vec.x, 0, screen_size_x - 1);
 			
 			tempf = ((float)sv->vec.y) * facy;
 			sv->vec.y = (short)(tempf + 0.5f);
 			//sv->vec.y += AREAGRID - 1;
 			//sv->vec.y -=  (sv->vec.y % AREAGRID);
 
-			CLAMP(sv->vec.y, 0, winsize_y - 1);
+			CLAMP(sv->vec.y, 0, screen_size_y);
 		}
 	}
 
 
 #ifdef USE_HEADER_SIZE_CLAMP
-	if (winsize_y_prev < winsize_y) {  /* growing? */
+	if (screen_size_y_prev < screen_size_y) {  /* growing? */
 		for (sa = sc->areabase.first; sa; sa = sa->next) {
 			ScrEdge *se = NULL;
 
@@ -610,7 +649,7 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 				const int yval = sa->v2->vec.y - headery_init;
 				se = BKE_screen_find_edge(sc, sa->v4, sa->v1);
 				if (se != NULL) {
-					select_connected_scredge(sc, se);
+					select_connected_scredge(win, se);
 				}
 				for (sv = sc->vertbase.first; sv; sv = sv->next) {
 					if (sv != sa->v2 && sv != sa->v3) {
@@ -625,7 +664,7 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 				const int yval = sa->v1->vec.y + headery_init;
 				se = BKE_screen_find_edge(sc, sa->v2, sa->v3);
 				if (se != NULL) {
-					select_connected_scredge(sc, se);
+					select_connected_scredge(win, se);
 				}
 				for (sv = sc->vertbase.first; sv; sv = sv->next) {
 					if (sv != sa->v1 && sv != sa->v4) {
@@ -654,7 +693,7 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 		/* adjust headery if verts are along the edge of window */
 		if (sa->v1->vec.y > 0)
 			headery += U.pixelsize;
-		if (sa->v2->vec.y < winsize_y - 1)
+		if (sa->v2->vec.y < screen_size_y)
 			headery += U.pixelsize;
 		
 		if (sa->v2->vec.y - sa->v1->vec.y + 1 < headery) {
@@ -663,7 +702,7 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 			if (se && sa->v1 != sa->v2) {
 				int yval;
 				
-				select_connected_scredge(sc, se);
+				select_connected_scredge(win, se);
 				
 				/* all selected vertices get the right offset */
 				yval = sa->v2->vec.y - headery + 1;
@@ -678,7 +717,17 @@ static void screen_test_scale(bScreen *sc, int winsize_x, int winsize_y)
 			}
 		}
 	}
-	
+
+	/* Global areas have a fixed size that only changes with the DPI. Here we ensure that exactly this size is set.
+	 * TODO Assumes global area to be top-aligned. Should be made more generic */
+	for (ScrArea *area = win->global_areas.areabase.first; area; area = area->next) {
+		/* width */
+		area->v1->vec.x = area->v2->vec.x = 0;
+		area->v3->vec.x = area->v4->vec.x = window_size_x - 1;
+		/* height */
+		area->v2->vec.y = area->v3->vec.y = window_size_y - 1;
+		area->v1->vec.y = area->v4->vec.y = area->v2->vec.y - ED_area_global_size_y(area);
+	}
 }
 
 
@@ -689,7 +738,7 @@ static void region_cursor_set(wmWindow *win, bool swin_changed)
 {
 	bScreen *screen = WM_window_get_active_screen(win);
 
-	for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
+	ED_screen_areas_iter(win, screen, sa) {
 		for (ARegion *ar = sa->regionbase.first; ar; ar = ar->next) {
 			if (ar == screen->active_region) {
 				if (swin_changed || (ar->type && ar->type->event_cursor)) {
@@ -751,20 +800,21 @@ void ED_screen_refresh(wmWindowManager *wm, wmWindow *win)
 
 	/* exception for bg mode, we only need the screen context */
 	if (!G.background) {
-		const int winsize_x = WM_window_pixels_x(win);
-		const int winsize_y = WM_window_pixels_y(win);
-		ScrArea *sa;
-		
+		const int window_size_x = WM_window_pixels_x(win);
+		const int window_size_y = WM_window_pixels_y(win);
+		const int screen_size_x = WM_window_screen_pixels_x(win);
+		const int screen_size_y = WM_window_screen_pixels_y(win);
+
 		/* header size depends on DPI, let's verify */
 		WM_window_set_dpi(win);
 		screen_refresh_headersizes();
-		
-		screen_test_scale(screen, winsize_x, winsize_y);
-		
-		for (sa = screen->areabase.first; sa; sa = sa->next) {
+
+		screen_vertices_scale(win, screen, window_size_x, window_size_y, screen_size_x, screen_size_y);
+
+		ED_screen_areas_iter(win, screen, area) {
 			/* set spacetype and region callbacks, calls init() */
 			/* sets subwindows for regions, adds handlers */
-			ED_area_initialize(wm, win, sa);
+			ED_area_initialize(wm, win, area);
 		}
 	
 		/* wake up animtimer */
@@ -782,6 +832,36 @@ void ED_screen_refresh(wmWindowManager *wm, wmWindow *win)
 	screen->context = ed_screen_context;
 }
 
+static bool screen_regions_need_size_refresh(
+        const wmWindow *win, const bScreen *screen)
+{
+	ED_screen_areas_iter(win, screen, area) {
+		if (area->flag & AREA_FLAG_REGION_SIZE_UPDATE) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static void screen_refresh_region_sizes_only(
+        wmWindowManager *wm, wmWindow *win,
+        bScreen *screen)
+{
+	const int window_size_x = WM_window_pixels_x(win);
+	const int window_size_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
+
+	screen_vertices_scale(win, screen, window_size_x, window_size_y, screen_size_x, screen_size_y);
+
+	ED_screen_areas_iter(win, screen, area) {
+		screen_area_update_region_sizes(wm, win, area);
+		/* XXX hack to force drawing */
+		ED_area_tag_redraw(area);
+	}
+}
+
 /* file read, set all screens, ... */
 void ED_screens_initialize(wmWindowManager *wm)
 {
@@ -792,8 +872,21 @@ void ED_screens_initialize(wmWindowManager *wm)
 			WM_window_set_active_workspace(win, G.main->workspaces.first);
 		}
 
+		if (BLI_listbase_is_empty(&win->global_areas.areabase)) {
+			ED_screen_global_areas_create(win);
+		}
+		ED_screen_refresh(wm, win);
+	}
+}
+
+void ED_screen_ensure_updated(wmWindowManager *wm, wmWindow *win, bScreen *screen)
+{
+	if (screen->do_refresh) {
 		ED_screen_refresh(wm, win);
 	}
+	else if (screen_regions_need_size_refresh(win, screen)) {
+		screen_refresh_region_sizes_only(wm, win, screen);
+	}
 }
 
 
@@ -872,6 +965,9 @@ void ED_screen_exit(bContext *C, wmWindow *window, bScreen *screen)
 	for (sa = screen->areabase.first; sa; sa = sa->next) {
 		ED_area_exit(C, sa);
 	}
+	for (sa = window->global_areas.areabase.first; sa; sa = sa->next) {
+		ED_area_exit(C, sa);
+	}
 
 	/* mark it available for use for other windows */
 	screen->winid = 0;
@@ -893,9 +989,6 @@ void ED_screen_exit(bContext *C, wmWindow *window, bScreen *screen)
 static void screen_cursor_set(wmWindow *win, const wmEvent *event)
 {
 	const bScreen *screen = WM_window_get_active_screen(win);
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
-
 	AZone *az = NULL;
 	ScrArea *sa;
 	
@@ -914,8 +1007,8 @@ static void screen_cursor_set(wmWindow *win, const wmEvent *event)
 		}
 	}
 	else {
-		ScrEdge *actedge = screen_find_active_scredge(screen, winsize_x, winsize_y, event->x, event->y);
-		
+		ScrEdge *actedge = screen_find_active_scredge(win, screen, event->x, event->y);
+
 		if (actedge) {
 			if (scredge_is_horizontal(actedge))
 				WM_cursor_set(win, CURSOR_Y_MOVE);
@@ -936,15 +1029,19 @@ void ED_screen_set_active_region(bContext *C, const wmEvent *event)
 	bScreen *scr = WM_window_get_active_screen(win);
 
 	if (scr) {
-		ScrArea *sa;
+		ScrArea *sa = NULL;
 		ARegion *ar;
 		ARegion *old_ar = scr->active_region;
 
-		for (sa = scr->areabase.first; sa; sa = sa->next) {
-			if (event->x > sa->totrct.xmin && event->x < sa->totrct.xmax)
-				if (event->y > sa->totrct.ymin && event->y < sa->totrct.ymax)
-					if (NULL == is_in_area_actionzone(sa, &event->x))
+		ED_screen_areas_iter(win, scr, area_iter) {
+			if (event->x > area_iter->totrct.xmin && event->x < area_iter->totrct.xmax) {
+				if (event->y > area_iter->totrct.ymin && event->y < area_iter->totrct.ymax) {
+					if (is_in_area_actionzone(area_iter, &event->x) == NULL) {
+						sa = area_iter;
 						break;
+					}
+				}
+			}
 		}
 		if (sa) {
 			/* make overlap active when mouse over */
@@ -961,17 +1058,21 @@ void ED_screen_set_active_region(bContext *C, const wmEvent *event)
 		/* check for redraw headers */
 		if (old_ar != scr->active_region) {
 
-			for (sa = scr->areabase.first; sa; sa = sa->next) {
+			ED_screen_areas_iter(win, scr, area_iter) {
 				bool do_draw = false;
 				
-				for (ar = sa->regionbase.first; ar; ar = ar->next)
-					if (ar == old_ar || ar == scr->active_region)
+				for (ar = area_iter->regionbase.first; ar; ar = ar->next) {
+					if (ar == old_ar || ar == scr->active_region) {
 						do_draw = true;
+					}
+				}
 				
 				if (do_draw) {
-					for (ar = sa->regionbase.first; ar; ar = ar->next)
-						if (ar->regiontype == RGN_TYPE_HEADER)
+					for (ar = area_iter->regionbase.first; ar; ar = ar->next) {
+						if (ar->regiontype == RGN_TYPE_HEADER) {
 							ED_region_tag_redraw(ar);
+						}
+					}
 				}
 			}
 		}
@@ -1016,6 +1117,47 @@ int ED_screen_area_active(const bContext *C)
 	return 0;
 }
 
+void ED_screen_global_topbar_area_create(wmWindow *win, const bScreen *screen)
+{
+	if (screen->temp == 0) {
+		SpaceType *st = BKE_spacetype_from_id(SPACE_TOPBAR);
+		SpaceLink *sl = st->new(NULL);
+		ScrArea *sa;
+		const short size_y = 2 * HEADERY;
+		const int minx = 0, maxx = WM_window_pixels_x(win) - 1;
+		const int maxy = WM_window_pixels_y(win) - 1, miny = maxy - size_y;
+
+		ScrVert *bottom_left  = screen_addvert_ex(&win->global_areas, minx, miny);
+		ScrVert *top_left     = screen_addvert_ex(&win->global_areas, minx, maxy);
+		ScrVert *top_right    = screen_addvert_ex(&win->global_areas, maxx, maxy);
+		ScrVert *bottom_right = screen_addvert_ex(&win->global_areas, maxx, miny);
+		screen_addedge_ex(&win->global_areas, bottom_left, top_left);
+		screen_addedge_ex(&win->global_areas, top_left, top_right);
+		screen_addedge_ex(&win->global_areas, top_right, bottom_right);
+		screen_addedge_ex(&win->global_areas, bottom_right, bottom_left);
+
+		sa = screen_addarea_ex(&win->global_areas, bottom_left, top_left, top_right, bottom_right,
+		                       HEADERTOP, SPACE_TOPBAR);
+		sa->regionbase = sl->regionbase;
+
+		/* Data specific to global areas. */
+		sa->global = MEM_callocN(sizeof(*sa->global), __func__);
+		sa->global->cur_fixed_height = size_y;
+		sa->global->size_max = size_y;
+		sa->global->size_min = HEADERY;
+
+		BLI_addhead(&sa->spacedata, sl);
+		BLI_listbase_clear(&sl->regionbase);
+	}
+	/* Do not create more area types here! Function is called on file load (wm_window_ghostwindows_ensure). TODO */
+}
+
+void ED_screen_global_areas_create(wmWindow *win)
+{
+	const bScreen *screen = BKE_workspace_active_screen_get(win->workspace_hook);
+	ED_screen_global_topbar_area_create(win, screen);
+}
+
 
 /* -------------------------------------------------------------------- */
 /* Screen changing */
@@ -1168,7 +1310,6 @@ void ED_screen_update_after_scene_change(const bScreen *screen, Scene *scene_new
 ScrArea *ED_screen_full_newspace(bContext *C, ScrArea *sa, int type)
 {
 	wmWindow *win = CTX_wm_window(C);
-	bScreen *screen = CTX_wm_screen(C);
 	ScrArea *newsa = NULL;
 
 	if (!sa || sa->full == NULL) {
@@ -1176,18 +1317,7 @@ ScrArea *ED_screen_full_newspace(bContext *C, ScrArea *sa, int type)
 	}
 	
 	if (!newsa) {
-		if (sa->full && (screen->state == SCREENMAXIMIZED)) {
-			/* if this has been called from the temporary info header generated in
-			 * temp fullscreen layouts, find the correct fullscreen area to change
-			 * to create a new space inside */
-			for (newsa = screen->areabase.first; newsa; newsa = newsa->next) {
-				if (!(sa->flag & AREA_TEMP_INFO))
-					break;
-			}
-		}
-		else {
-			newsa = sa;
-		}
+		newsa = sa;
 	}
 
 	BLI_assert(newsa);
@@ -1308,10 +1438,8 @@ ScrArea *ED_screen_state_toggle(bContext *C, wmWindow *win, ScrArea *sa, const s
 
 			/* clear full screen state */
 			old->full = NULL;
-			old->flag &= ~AREA_TEMP_INFO;
 		}
 
-		sa->flag &= ~AREA_TEMP_INFO;
 		sa->full = NULL;
 
 		if (fullsa == NULL) {
@@ -1349,6 +1477,8 @@ ScrArea *ED_screen_state_toggle(bContext *C, wmWindow *win, ScrArea *sa, const s
 		ScrArea *newa;
 		char newname[MAX_ID_NAME - 2];
 
+		BLI_assert(ELEM(state, SCREENMAXIMIZED, SCREENFULL));
+
 		oldscreen = WM_window_get_active_screen(win);
 
 		oldscreen->state = state;
@@ -1367,50 +1497,30 @@ ScrArea *ED_screen_state_toggle(bContext *C, wmWindow *win, ScrArea *sa, const s
 
 		/* use random area when we have no active one, e.g. when the
 		 * mouse is outside of the window and we open a file browser */
-		if (!sa)
+		if (!sa) {
 			sa = oldscreen->areabase.first;
-
-		if (state == SCREENMAXIMIZED) {
-			/* returns the top small area */
-			newa = area_split(sc, (ScrArea *)sc->areabase.first, 'h', 0.99f, 1);
-			ED_area_newspace(C, newa, SPACE_INFO, false);
-
-			/* copy area */
-			newa = newa->prev;
-			ED_area_data_swap(newa, sa);
-			sa->flag |= AREA_TEMP_INFO;
-
-			sa->full = oldscreen;
-			newa->full = oldscreen;
-			newa->next->full = oldscreen; // XXX
 		}
-		else if (state == SCREENFULL) {
-			newa = (ScrArea *)sc->areabase.first;
 
-			/* copy area */
-			ED_area_data_swap(newa, sa);
-			newa->flag = sa->flag; /* mostly for AREA_FLAG_WASFULLSCREEN */
+		newa = (ScrArea *)sc->areabase.first;
+
+		/* copy area */
+		ED_area_data_swap(newa, sa);
+		newa->flag = sa->flag; /* mostly for AREA_FLAG_WASFULLSCREEN */
 
+		if (state == SCREENFULL) {
 			/* temporarily hide the side panels/header */
 			for (ar = newa->regionbase.first; ar; ar = ar->next) {
 				ar->flagfullscreen = ar->flag;
 
-				if (ELEM(ar->regiontype,
-				         RGN_TYPE_UI,
-				         RGN_TYPE_HEADER,
-				         RGN_TYPE_TOOLS))
-				{
+				if (ELEM(ar->regiontype, RGN_TYPE_UI, RGN_TYPE_HEADER, RGN_TYPE_TOOLS)){
 					ar->flag |= RGN_FLAG_HIDDEN;
 				}
 			}
-
-			sa->full = oldscreen;
-			newa->full = oldscreen;
-		}
-		else {
-			BLI_assert(false);
 		}
 
+		sa->full = oldscreen;
+		newa->full = oldscreen;
+
 		ED_screen_change(C, sc);
 	}
 
diff --git a/source/blender/editors/screen/screen_intern.h b/source/blender/editors/screen/screen_intern.h
index 606838ae890..045e5ee6b48 100644
--- a/source/blender/editors/screen/screen_intern.h
+++ b/source/blender/editors/screen/screen_intern.h
@@ -44,6 +44,7 @@ struct Main;
 /* area.c */
 void        ED_area_data_copy(ScrArea *sa_dst, ScrArea *sa_src, const bool do_free);
 void        ED_area_data_swap(ScrArea *sa1, ScrArea *sa2);
+void        screen_area_update_region_sizes(wmWindowManager *wm, wmWindow *win, ScrArea *area);
 void        region_toggle_hidden(struct bContext *C, ARegion *ar, const bool do_fade);
 
 /* screen_edit.c */
@@ -55,12 +56,16 @@ bScreen    *screen_change_prepare(bScreen *screen_old, bScreen *screen_new, stru
 ScrArea    *area_split(bScreen *sc, ScrArea *sa, char dir, float fac, int merge);
 int         screen_area_join(struct bContext *C, bScreen *scr, ScrArea *sa1, ScrArea *sa2);
 int         area_getorientation(ScrArea *sa, ScrArea *sb);
-void        select_connected_scredge(bScreen *sc, ScrEdge *edge);
+void        select_connected_scredge(const wmWindow *win, ScrEdge *edge);
 
 bool        scredge_is_horizontal(ScrEdge *se);
-ScrEdge    *screen_find_active_scredge(const bScreen *sc,
-                                       const int winsize_x, const int winsize_y,
-                                       const int mx, const int my);
+ScrEdge     *screen_area_map_find_active_scredge(
+        const struct ScrAreaMap *area_map,
+        const int winsize_x, const int winsize_y,
+        const int mx, const int my);
+ScrEdge    *screen_find_active_scredge(
+        const wmWindow *win, const bScreen *screen,
+        const int mx, const int my);
 
 struct AZone *is_in_area_actionzone(ScrArea *sa, const int xy[2]);
 
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index 25d5fbbdc4c..8b889c61deb 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -791,8 +791,8 @@ static int actionzone_modal(bContext *C, wmOperator *op, const wmEvent *event)
 	wmWindow *win = CTX_wm_window(C);
 	bScreen *sc = CTX_wm_screen(C);
 	sActionzoneData *sad = op->customdata;
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
 
 	switch (event->type) {
 		case MOUSEMOVE:
@@ -816,7 +816,8 @@ static int actionzone_modal(bContext *C, wmOperator *op, const wmEvent *event)
 				/* once we drag outside the actionzone, register a gesture
 				 * check we're not on an edge so join finds the other area */
 				is_gesture = ((is_in_area_actionzone(sad->sa1, &event->x) != sad->az) &&
-				              (screen_find_active_scredge(sc, winsize_x, winsize_y, event->x, event->y) == NULL));
+				              (screen_area_map_find_active_scredge(
+				                   AREAMAP_FROM_SCREEN(sc), screen_size_x, screen_size_y, event->x, event->y) == NULL));
 			}
 			else {
 				const int delta_min = 1;
@@ -1049,6 +1050,7 @@ static int area_dupli_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 	layout_new = ED_workspace_layout_add(workspace, newwin, BKE_workspace_layout_name_get(layout_old));
 	newsc = BKE_workspace_layout_screen_get(layout_new);
 	WM_window_set_active_layout(newwin, workspace, layout_new);
+	ED_screen_global_areas_create(newwin);
 
 	/* copy area to new screen */
 	ED_area_data_copy((ScrArea *)newsc->areabase.first, sa, true);
@@ -1116,25 +1118,73 @@ static void SCREEN_OT_area_dupli(wmOperatorType *ot)
  */
 
 typedef struct sAreaMoveData {
-	int bigger, smaller, origval;
+	int bigger, smaller, origval, step;
 	char dir;
-	bool do_snap;
+	enum AreaMoveSnapType {
+		/* Snapping disabled */
+		SNAP_NONE = 0,
+		/* Snap to mid-point and adjacent edges. */
+		SNAP_MIDPOINT_AND_ADJACENT,
+		/* Snap to either bigger or smaller, nothing in-between (used for
+		 * global areas). This has priority over other snap types, if it is
+		 * used, toggling SNAP_MIDPOINT_AND_ADJACENT doesn't work. */
+		SNAP_BIGGER_SMALLER_ONLY,
+	} snap_type;
 } sAreaMoveData;
 
 /* helper call to move area-edge, sets limits
  * need window size in order to get correct limits */
-static void area_move_set_limits(bScreen *sc, int dir,
-                                 const int winsize_x, const int winsize_y,
-                                 int *bigger, int *smaller)
+static void area_move_set_limits(
+        wmWindow *win, bScreen *sc, int dir,
+        const int winsize_x, const int winsize_y,
+        int *bigger, int *smaller,
+        bool *use_bigger_smaller_snap)
 {
-	ScrArea *sa;
 	int areaminy = ED_area_headersize();
 	int areamin;
-	
+
 	/* we check all areas and test for free space with MINSIZE */
 	*bigger = *smaller = 100000;
-	
-	for (sa = sc->areabase.first; sa; sa = sa->next) {
+
+	if (use_bigger_smaller_snap != NULL) {
+		*use_bigger_smaller_snap = false;
+		for (ScrArea *area = win->global_areas.areabase.first; area; area = area->next) {
+			const int size_min = round_fl_to_int(area->global->size_min * UI_DPI_FAC);
+			const int size_max = round_fl_to_int(area->global->size_max * UI_DPI_FAC);
+
+			/* logic here is only tested for lower edge :) */
+			/* left edge */
+			if ((area->v1->editflag && area->v2->editflag)) {
+				*smaller = area->v4->vec.x - size_max;
+				*bigger  = area->v4->vec.x - size_min;
+				*use_bigger_smaller_snap = true;
+				return;
+			}
+			/* top edge */
+			else if ((area->v2->editflag && area->v3->editflag)) {
+				*smaller = area->v1->vec.y + size_min;
+				*bigger  = area->v1->vec.y + size_max;
+				*use_bigger_smaller_snap = true;
+				return;
+			}
+			/* right edge */
+			else if ((area->v3->editflag && area->v4->editflag)) {
+				*smaller = area->v1->vec.x + size_min;
+				*bigger  = area->v1->vec.x + size_max;
+				*use_bigger_smaller_snap = true;
+				return;
+			}
+			/* lower edge */
+			else if ((area->v4->editflag && area->v1->editflag)) {
+				*smaller = area->v2->vec.y - size_max;
+				*bigger  = area->v2->vec.y - size_min;
+				*use_bigger_smaller_snap = true;
+				return;
+			}
+		}
+	}
+
+	for (ScrArea *sa = sc->areabase.first; sa; sa = sa->next) {
 		if (dir == 'h') {
 			int y1;
 			areamin = areaminy;
@@ -1180,9 +1230,8 @@ static int area_move_init(bContext *C, wmOperator *op)
 	wmWindow *win = CTX_wm_window(C);
 	ScrEdge *actedge;
 	sAreaMoveData *md;
-	ScrVert *v1;
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
 	int x, y;
 	
 	/* required properties */
@@ -1190,7 +1239,7 @@ static int area_move_init(bContext *C, wmOperator *op)
 	y = RNA_int_get(op->ptr, "y");
 	
 	/* setup */
-	actedge = screen_find_active_scredge(sc, winsize_x, winsize_y, x, y);
+	actedge = screen_find_active_scredge(win, sc, x, y);
 	if (actedge == NULL) return 0;
 	
 	md = MEM_callocN(sizeof(sAreaMoveData), "sAreaMoveData");
@@ -1200,23 +1249,33 @@ static int area_move_init(bContext *C, wmOperator *op)
 	if (md->dir == 'h') md->origval = actedge->v1->vec.y;
 	else md->origval = actedge->v1->vec.x;
 	
-	select_connected_scredge(sc, actedge);
-	/* now all vertices with 'flag==1' are the ones that can be moved. Move this to editflag */
-	for (v1 = sc->vertbase.first; v1; v1 = v1->next)
+	select_connected_scredge(win, actedge);
+	/* now all vertices with 'flag == 1' are the ones that can be moved. Move this to editflag */
+	ED_screen_verts_iter(win, sc, v1) {
 		v1->editflag = v1->flag;
-	
-	area_move_set_limits(sc, md->dir, winsize_x, winsize_y, &md->bigger, &md->smaller);
-	
+	}
+
+	bool use_bigger_smaller_snap = false;
+	area_move_set_limits(win, sc, md->dir, screen_size_x, screen_size_y,
+	                     &md->bigger, &md->smaller,
+	                     &use_bigger_smaller_snap);
+
+	md->snap_type = use_bigger_smaller_snap ? SNAP_BIGGER_SMALLER_ONLY : SNAP_NONE;
+
 	return 1;
 }
 
 static int area_snap_calc_location(
-        const bScreen *sc, const int delta,
-        const int origval, const int dir,
+        const bScreen *sc, const enum AreaMoveSnapType snap_type,
+        const int delta, const int origval, const int dir,
         const int bigger, const int smaller)
 {
-	int final_loc = -1;
+	BLI_assert(snap_type != SNAP_NONE);
+	if (snap_type == SNAP_BIGGER_SMALLER_ONLY) {
+		return ((origval + delta) >= bigger) ? bigger : smaller;
+	}
 
+	int final_loc = -1;
 	const int m_loc = origval + delta;
 	const int axis = (dir == 'v') ? 0 : 1;
 	int snap_dist;
@@ -1260,29 +1319,29 @@ static void area_move_apply_do(
         const bContext *C, int delta,
         const int origval, const int dir,
         const int bigger, const int smaller,
-        const bool do_snap)
+        const enum AreaMoveSnapType snap_type)
 {
+	wmWindow *win = CTX_wm_window(C);
 	bScreen *sc = CTX_wm_screen(C);
-	ScrVert *v1;
 	bool doredraw = false;
 	CLAMP(delta, -smaller, bigger);
 
 	short final_loc = -1;
 
-	if (do_snap) {
-		final_loc = area_snap_calc_location(sc, delta, origval, dir, bigger, smaller);
-	}
-	else {
+	if (snap_type == SNAP_NONE) {
 		final_loc = origval + delta;
 		if (delta != bigger && delta != -smaller) {
 			final_loc -= (final_loc % AREAGRID);
 		}
 	}
+	else {
+		final_loc = area_snap_calc_location(sc, snap_type, delta, origval, dir, bigger, smaller);
+	}
 
 	BLI_assert(final_loc != -1);
 	short axis = (dir == 'v') ? 0 : 1;
 
-	for (v1 = sc->vertbase.first; v1; v1 = v1->next) {
+	ED_screen_verts_iter(win, sc, v1) {
 		if (v1->editflag) {
 			short oldval = (&v1->vec.x)[axis];
 			(&v1->vec.x)[axis] = final_loc;
@@ -1297,11 +1356,23 @@ static void area_move_apply_do(
 
 	/* only redraw if we actually moved a screen vert, for AREAGRID */
 	if (doredraw) {
-		for (ScrArea *sa = sc->areabase.first; sa; sa = sa->next) {
+		bool redraw_all = false;
+		ED_screen_areas_iter(win, sc, sa) {
 			if (sa->v1->editflag || sa->v2->editflag || sa->v3->editflag || sa->v4->editflag) {
+				if (ED_area_is_global(sa)) {
+					sa->global->cur_fixed_height = round_fl_to_int((sa->v2->vec.y - sa->v1->vec.y) / UI_DPI_FAC);
+					sc->do_refresh = true;
+					redraw_all = true;
+				}
 				ED_area_tag_redraw(sa);
 			}
 		}
+		if (redraw_all) {
+			ED_screen_areas_iter(win, sc, sa) {
+				ED_area_tag_redraw(sa);
+			}
+		}
+
 		WM_event_add_notifier(C, NC_SCREEN | NA_EDITED, NULL); /* redraw everything */
 		/* Update preview thumbnail */
 		BKE_icon_changed(sc->id.icon_id);
@@ -1313,7 +1384,7 @@ static void area_move_apply(bContext *C, wmOperator *op)
 	sAreaMoveData *md = op->customdata;
 	int delta = RNA_int_get(op->ptr, "delta");
 
-	area_move_apply_do(C, delta, md->origval, md->dir, md->bigger, md->smaller, md->do_snap);
+	area_move_apply_do(C, delta, md->origval, md->dir, md->bigger, md->smaller, md->snap_type);
 }
 
 static void area_move_exit(bContext *C, wmOperator *op)
@@ -1392,10 +1463,14 @@ static int area_move_modal(bContext *C, wmOperator *op, const wmEvent *event)
 					return OPERATOR_CANCELLED;
 
 				case KM_MODAL_SNAP_ON:
-					md->do_snap = true;
+					if (md->snap_type == SNAP_NONE) {
+						md->snap_type = SNAP_MIDPOINT_AND_ADJACENT;
+					}
 					break;
 				case KM_MODAL_SNAP_OFF:
-					md->do_snap = false;
+					if (md->snap_type == SNAP_MIDPOINT_AND_ADJACENT) {
+						md->snap_type = SNAP_NONE;
+					}
 					break;
 			}
 			break;
@@ -1644,8 +1719,8 @@ static int area_split_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 	wmWindow *win = CTX_wm_window(C);
 	bScreen *sc = CTX_wm_screen(C);
 	sAreaSplitData *sd;
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
 	int dir;
 	
 	/* no full window splitting allowed */
@@ -1698,7 +1773,7 @@ static int area_split_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 		else
 			y = event->x;
 		
-		actedge = screen_find_active_scredge(sc, winsize_x, winsize_y, x, y);
+		actedge = screen_area_map_find_active_scredge(AREAMAP_FROM_SCREEN(sc), screen_size_x, screen_size_y, x, y);
 		if (actedge == NULL)
 			return OPERATOR_CANCELLED;
 		
@@ -1718,7 +1793,7 @@ static int area_split_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 		
 		/* do the split */
 		if (area_split_apply(C, op)) {
-			area_move_set_limits(sc, dir, winsize_x, winsize_y, &sd->bigger, &sd->smaller);
+			area_move_set_limits(win, sc, dir, screen_size_x, screen_size_y, &sd->bigger, &sd->smaller, NULL);
 			
 			/* add temp handler for edge move or cancel */
 			WM_event_add_modal_handler(C, op);
@@ -1836,10 +1911,11 @@ static int area_split_modal(bContext *C, wmOperator *op, const wmEvent *event)
 		if (sd->previewmode == 0) {
 			if (sd->do_snap) {
 				const int snap_loc = area_snap_calc_location(
-				        CTX_wm_screen(C), sd->delta, sd->origval, dir, sd->bigger, sd->smaller);
+				        CTX_wm_screen(C), SNAP_MIDPOINT_AND_ADJACENT, sd->delta, sd->origval, dir,
+				        sd->bigger, sd->smaller);
 				sd->delta = snap_loc - sd->origval;
 			}
-			area_move_apply_do(C, sd->delta, sd->origval, dir, sd->bigger, sd->smaller, false);
+			area_move_apply_do(C, sd->delta, sd->origval, dir, sd->bigger, sd->smaller, SNAP_NONE);
 		}
 		else {
 			if (sd->sarea) {
@@ -1863,7 +1939,8 @@ static int area_split_modal(bContext *C, wmOperator *op, const wmEvent *event)
 					sa->v1->editflag = sa->v2->editflag = sa->v3->editflag = sa->v4->editflag = 1;
 
 					const int snap_loc = area_snap_calc_location(
-					        CTX_wm_screen(C), sd->delta, sd->origval, dir, sd->origmin + sd->origsize, -sd->origmin);
+					        CTX_wm_screen(C), SNAP_MIDPOINT_AND_ADJACENT, sd->delta, sd->origval, dir,
+					        sd->origmin + sd->origsize, -sd->origmin);
 
 					sa->v1->editflag = sa->v2->editflag = sa->v3->editflag = sa->v4->editflag = 0;
 					sd->delta = snap_loc - sd->origval;
@@ -2579,6 +2656,14 @@ static int screen_maximize_area_exec(bContext *C, wmOperator *op)
 	return OPERATOR_FINISHED;
 }
 
+static int screen_maximize_area_poll(bContext *C)
+{
+	const bScreen *screen = CTX_wm_screen(C);
+	const ScrArea *area = CTX_wm_area(C);
+	return ED_operator_areaactive(C) &&
+	       ((screen->state != SCREENNORMAL) || (area->spacetype != SPACE_TOPBAR));
+}
+
 static void SCREEN_OT_screen_full_area(wmOperatorType *ot)
 {
 	PropertyRNA *prop;
@@ -2588,7 +2673,7 @@ static void SCREEN_OT_screen_full_area(wmOperatorType *ot)
 	ot->idname = "SCREEN_OT_screen_full_area";
 	
 	ot->exec = screen_maximize_area_exec;
-	ot->poll = ED_operator_areaactive;
+	ot->poll = screen_maximize_area_poll;
 	ot->flag = 0;
 
 	prop = RNA_def_boolean(ot->srna, "use_hide_panels", false, "Hide Panels", "Hide all the panels");
@@ -2898,10 +2983,11 @@ static int screen_area_options_invoke(bContext *C, wmOperator *op, const wmEvent
 	uiLayout *layout;
 	PointerRNA ptr;
 	ScrEdge *actedge;
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
 
-	actedge = screen_find_active_scredge(sc, winsize_x, winsize_y, event->x, event->y);
+	actedge = screen_area_map_find_active_scredge(
+	              AREAMAP_FROM_SCREEN(sc), screen_size_x, screen_size_y, event->x, event->y);
 	
 	if (actedge == NULL) return OPERATOR_CANCELLED;
 	
@@ -3305,6 +3391,18 @@ static int region_flip_exec(bContext *C, wmOperator *UNUSED(op))
 	return OPERATOR_FINISHED;
 }
 
+static int region_flip_poll(bContext *C)
+{
+	ScrArea *area = CTX_wm_area(C);
+
+	/* don't flip anything around in topbar */
+	if (area->spacetype == SPACE_TOPBAR) {
+		CTX_wm_operator_poll_msg_set(C, "Flipping regions in the Top-bar is not allowed");
+		return 0;
+	}
+
+	return ED_operator_areaactive(C);
+}
 
 static void SCREEN_OT_region_flip(wmOperatorType *ot)
 {
@@ -3315,7 +3413,7 @@ static void SCREEN_OT_region_flip(wmOperatorType *ot)
 	
 	/* api callbacks */
 	ot->exec = region_flip_exec;
-	ot->poll = ED_operator_areaactive;
+	ot->poll = region_flip_poll;
 	ot->flag = 0;
 }
 
@@ -3408,12 +3506,11 @@ void ED_screens_header_tools_menu_create(bContext *C, uiLayout *layout, void *UN
 
 	uiItemS(layout);
 
-	/* file browser should be fullscreen all the time, but other regions can be maximized/restored... */
-	if (sa->spacetype != SPACE_FILE) {
-		if (sa->full) 
-			uiItemO(layout, IFACE_("Tile Area"), ICON_NONE, "SCREEN_OT_screen_full_area");
-		else
-			uiItemO(layout, IFACE_("Maximize Area"), ICON_NONE, "SCREEN_OT_screen_full_area");
+	/* file browser should be fullscreen all the time, topbar should
+	 * never be. But other regions can be maximized/restored... */
+	if (!ELEM(sa->spacetype, SPACE_FILE, SPACE_TOPBAR)) {
+		const char *but_str = sa->full ? IFACE_("Tile Area") : IFACE_("Maximize Area");
+		uiItemO(layout, but_str, ICON_NONE, "SCREEN_OT_screen_full_area");
 	}
 }
 
diff --git a/source/blender/editors/screen/screendump.c b/source/blender/editors/screen/screendump.c
index 69891a727d4..2c1cbc3d21d 100644
--- a/source/blender/editors/screen/screendump.c
+++ b/source/blender/editors/screen/screendump.c
@@ -275,7 +275,7 @@ static void screenshot_draw(bContext *UNUSED(C), wmOperator *op)
 
 	/* main draw call */
 	RNA_pointer_create(NULL, op->type->srna, op->properties, &ptr);
-	uiDefAutoButsRNA(layout, &ptr, screenshot_draw_check_prop, '\0');
+	uiDefAutoButsRNA(layout, &ptr, screenshot_draw_check_prop, UI_BUT_LABEL_ALIGN_NONE, false);
 }
 
 static int screenshot_poll(bContext *C)
diff --git a/source/blender/editors/screen/workspace_edit.c b/source/blender/editors/screen/workspace_edit.c
index b40eef8a38f..c8aa4560dc4 100644
--- a/source/blender/editors/screen/workspace_edit.c
+++ b/source/blender/editors/screen/workspace_edit.c
@@ -313,11 +313,9 @@ static void WORKSPACE_OT_workspace_duplicate(wmOperatorType *ot)
 
 static int workspace_delete_exec(bContext *C, wmOperator *UNUSED(op))
 {
-	Main *bmain = CTX_data_main(C);
-	wmWindowManager *wm = CTX_wm_manager(C);
 	wmWindow *win = CTX_wm_window(C);
 
-	ED_workspace_delete(WM_window_get_active_workspace(win), bmain, C, wm);
+	WM_event_add_notifier(C, NC_SCREEN | ND_WORKSPACE_DELETE, WM_window_get_active_workspace(win));
 
 	return OPERATOR_FINISHED;
 }
diff --git a/source/blender/editors/screen/workspace_layout_edit.c b/source/blender/editors/screen/workspace_layout_edit.c
index d84df160125..a6f991d4bbe 100644
--- a/source/blender/editors/screen/workspace_layout_edit.c
+++ b/source/blender/editors/screen/workspace_layout_edit.c
@@ -50,10 +50,10 @@ WorkSpaceLayout *ED_workspace_layout_add(
         wmWindow *win,
         const char *name)
 {
-	const int winsize_x = WM_window_pixels_x(win);
-	const int winsize_y = WM_window_pixels_y(win);
+	const int screen_size_x = WM_window_screen_pixels_x(win);
+	const int screen_size_y = WM_window_screen_pixels_y(win);
 
-	bScreen *screen = screen_add(name, winsize_x, winsize_y);
+	bScreen *screen = screen_add(name, screen_size_x, screen_size_y);
 	WorkSpaceLayout *layout = BKE_workspace_layout_add(workspace, screen, name);
 
 	return layout;