UI: Enable writing global area data (top-bar, status-bar) to .blend's

There should not be much user visible here (other than T73668 being addressed).

I added the writing code already for the initial implementation of workspaces,
but we decided to keep it disabled until the top-bar design is more clear. It
was never planned to keep this disabled for so long.

Fixes T73668.

source/blender/blenkernel/intern/screen.c

@@ -1368,14 +1368,12 @@ static void write_area_regions(BlendWriter *writer, ScrArea *area)
       }
       BLO_write_struct(writer, SpaceConsole, sl);
     }
-#ifdef WITH_GLOBAL_AREA_WRITING
     else if (sl->spacetype == SPACE_TOPBAR) {
       BLO_write_struct(writer, SpaceTopBar, sl);
     }
     else if (sl->spacetype == SPACE_STATUSBAR) {
       BLO_write_struct(writer, SpaceStatusBar, sl);
     }
-#endif
     else if (sl->spacetype == SPACE_USERPREF) {
       BLO_write_struct(writer, SpaceUserPref, sl);
     }
@@ -1397,9 +1395,7 @@ void BKE_screen_area_map_blend_write(BlendWriter *writer, ScrAreaMap *area_map)
 
     BLO_write_struct(writer, ScrArea, area);
 
-#ifdef WITH_GLOBAL_AREA_WRITING
     BLO_write_struct(writer, ScrGlobalAreaData, area->global);
-#endif
 
     write_area_regions(writer, area);
 

source/blender/blenloader/intern/writefile.c

@@ -1639,12 +1639,6 @@ static void write_windowmanager(BlendWriter *writer, wmWindowManager *wm, const
   write_wm_xr_data(writer, &wm->xr);
 
   LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
-#ifndef WITH_GLOBAL_AREA_WRITING
-    /* Don't write global areas yet, while we make changes to them. */
-    ScrAreaMap global_areas = win->global_areas;
-    memset(&win->global_areas, 0, sizeof(win->global_areas));
-#endif
-
     /* update deprecated screen member (for so loading in 2.7x uses the correct screen) */
     win->screen = BKE_workspace_active_screen_get(win->workspace_hook);
 
@@ -1652,11 +1646,7 @@ static void write_windowmanager(BlendWriter *writer, wmWindowManager *wm, const
     BLO_write_struct(writer, WorkSpaceInstanceHook, win->workspace_hook);
     BLO_write_struct(writer, Stereo3dFormat, win->stereo3d_format);
 
-#ifdef WITH_GLOBAL_AREA_WRITING
     BKE_screen_area_map_blend_write(writer, &win->global_areas);
-#else
-    win->global_areas = global_areas;
-#endif
 
     /* data is written, clear deprecated data again */
     win->screen = NULL;

source/blender/makesdna/DNA_screen_types.h

@@ -322,10 +322,6 @@ typedef struct uiPreview {
   char _pad1[6];
 } uiPreview;
 
-/* These two lines with # tell makesdna this struct can be excluded.
- * Should be: #ifndef WITH_GLOBAL_AREA_WRITING */
-#
-#
 typedef struct ScrGlobalAreaData {
   /* Global areas have a non-dynamic size. That means, changing the window
    * size doesn't affect their size at all. However, they can still be

source/blender/makesdna/DNA_space_types.h

@@ -59,10 +59,6 @@ struct wmTimer;
 /* Defined in `buttons_intern.h`. */
 typedef struct SpaceProperties_Runtime SpaceProperties_Runtime;
 
-/* TODO 2.8: We don't write the global areas to files currently. Uncomment
- * define to enable writing (should become the default in a bit). */
-//#define WITH_GLOBAL_AREA_WRITING
-
 /* -------------------------------------------------------------------- */
 /** \name SpaceLink (Base)
  * \{ */
@@ -1672,10 +1668,6 @@ typedef enum eSpaceClip_GPencil_Source {
 /** \name Top Bar
  * \{ */
 
-/* These two lines with # tell makesdna this struct can be excluded.
- * Should be: #ifndef WITH_GLOBAL_AREA_WRITING */
-#
-#
 typedef struct SpaceTopBar {
   SpaceLink *next, *prev;
   /** Storage of regions for inactive spaces. */
@@ -1692,10 +1684,6 @@ typedef struct SpaceTopBar {
 /** \name Status Bar
  * \{ */
 
-/* These two lines with # tell makesdna this struct can be excluded.
- * Should be: #ifndef WITH_GLOBAL_AREA_WRITING */
-#
-#
 typedef struct SpaceStatusBar {
   SpaceLink *next, *prev;
   /** Storage of regions for inactive spaces. */