diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index a76a72d7910..c0a63e9f901 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -29,7 +29,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 11
+#define BLENDER_FILE_SUBVERSION 12
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and cancel loading the file, showing a warning to
diff --git a/source/blender/blenloader/intern/versioning_400.cc b/source/blender/blenloader/intern/versioning_400.cc
index d40bfac27cd..0c272428902 100644
--- a/source/blender/blenloader/intern/versioning_400.cc
+++ b/source/blender/blenloader/intern/versioning_400.cc
@@ -436,19 +436,7 @@ void blo_do_versions_400(FileData *fd, Library * /*lib*/, Main *bmain)
     version_vertex_weight_edit_preserve_threshold_exclusivity(bmain);
   }
 
-  /**
-   * Versioning code until next subversion bump goes here.
-   *
-   * \note Be sure to check when bumping the version:
-   * - #do_versions_after_linking_400 in this file.
-   * - "versioning_userdef.c", #blo_do_versions_userdef
-   * - "versioning_userdef.c", #do_versions_theme
-   *
-   * \note Keep this message at the bottom of the function.
-   */
-  {
-    /* Keep this block, even when empty. */
-
+  if (!MAIN_VERSION_FILE_ATLEAST(bmain, 400, 12)) {
     if (!DNA_struct_elem_find(fd->filesdna, "LightProbe", "int", "grid_bake_samples")) {
       LISTBASE_FOREACH (LightProbe *, lightprobe, &bmain->lightprobes) {
         lightprobe->grid_bake_samples = 2048;
@@ -498,5 +486,36 @@ void blo_do_versions_400(FileData *fd, Library * /*lib*/, Main *bmain)
       }
     }
     FOREACH_NODETREE_END;
+
+    LISTBASE_FOREACH (bScreen *, screen, &bmain->screens) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                 &sl->regionbase;
+
+          /* Layout based regions used to also disallow resizing, now these are separate flags.
+           * Make sure they are set together for old regions. */
+          LISTBASE_FOREACH (ARegion *, region, regionbase) {
+            if (region->flag & RGN_FLAG_DYNAMIC_SIZE) {
+              region->flag |= RGN_FLAG_NO_USER_RESIZE;
+            }
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Versioning code until next subversion bump goes here.
+   *
+   * \note Be sure to check when bumping the version:
+   * - #do_versions_after_linking_400 in this file.
+   * - "versioning_userdef.c", #blo_do_versions_userdef
+   * - "versioning_userdef.c", #do_versions_theme
+   *
+   * \note Keep this message at the bottom of the function.
+   */
+  {
+    /* Keep this block, even when empty. */
   }
 }
diff --git a/source/blender/blenloader/intern/versioning_userdef.cc b/source/blender/blenloader/intern/versioning_userdef.cc
index 133e4409879..7786923ebd0 100644
--- a/source/blender/blenloader/intern/versioning_userdef.cc
+++ b/source/blender/blenloader/intern/versioning_userdef.cc
@@ -105,6 +105,11 @@ static void do_versions_theme(const UserDef *userdef, bTheme *btheme)
     FROM_DEFAULT_V4_UCHAR(space_node.node_zone_simulation);
     FROM_DEFAULT_V4_UCHAR(space_action.simulated_frames);
   }
+
+  if (!USER_VERSION_ATLEAST(400, 12)) {
+    FROM_DEFAULT_V4_UCHAR(space_node.node_zone_repeat);
+  }
+
   /**
    * Versioning code until next subversion bump goes here.
    *
@@ -116,7 +121,6 @@ static void do_versions_theme(const UserDef *userdef, bTheme *btheme)
    */
   {
     /* Keep this block, even when empty. */
-    FROM_DEFAULT_V4_UCHAR(space_node.node_zone_repeat);
   }
 
 #undef FROM_DEFAULT_V4_UCHAR
@@ -830,6 +834,15 @@ void blo_do_versions_userdef(UserDef *userdef)
     BKE_addon_remove_safe(&userdef->addons, "io_scene_obj");
   }
 
+  if (!USER_VERSION_ATLEAST(400, 12)) {
+#ifdef __APPLE__
+    /* Drop OpenGL support on MAC devices as they don't support OpenGL 4.3. */
+    if (userdef->gpu_backend == GPU_BACKEND_OPENGL) {
+      userdef->gpu_backend = GPU_BACKEND_METAL;
+    }
+#endif
+  }
+
   /**
    * Versioning code until next subversion bump goes here.
    *
@@ -841,13 +854,6 @@ void blo_do_versions_userdef(UserDef *userdef)
    */
   {
     /* Keep this block, even when empty. */
-
-#ifdef __APPLE__
-    /* Drop OpenGL support on MAC devices as they don't support OpenGL 4.3. */
-    if (userdef->gpu_backend == GPU_BACKEND_OPENGL) {
-      userdef->gpu_backend = GPU_BACKEND_METAL;
-    }
-#endif
   }
 
   LISTBASE_FOREACH (bTheme *, btheme, &userdef->themes) {
diff --git a/source/blender/editors/screen/area.cc b/source/blender/editors/screen/area.cc
index 6b7b9244907..2a3a742a4ee 100644
--- a/source/blender/editors/screen/area.cc
+++ b/source/blender/editors/screen/area.cc
@@ -1345,8 +1345,8 @@ static void region_rect_recursive(
     alignment = RGN_ALIGN_NONE;
   }
 
-  /* If both the #ARegion.sizex/y and the #ARegionType.prefsizex/y are 0,
-   * the region is tagged as too small, even before the layout for dynamic regions is created.
+  /* If both the #ARegion.sizex/y and the #ARegionType.prefsizex/y are 0, the region is tagged as
+   * too small, even before the layout for dynamically sized regions is created.
    * #wm_draw_window_offscreen() allows the layout to be created despite the #RGN_FLAG_TOO_SMALL
    * flag being set. But there may still be regions that don't have a separate #ARegionType.layout
    * callback. For those, set a default #ARegionType.prefsizex/y so they can become visible. */
@@ -1364,11 +1364,7 @@ static void region_rect_recursive(
                   ((region->sizex > 1) ? region->sizex + 0.5f : region->type->prefsizex);
   int prefsizey;
 
-  if (region->flag & RGN_FLAG_PREFSIZE_OR_HIDDEN) {
-    prefsizex = UI_SCALE_FAC * region->type->prefsizex;
-    prefsizey = UI_SCALE_FAC * region->type->prefsizey;
-  }
-  else if (region->regiontype == RGN_TYPE_HEADER) {
+  if (region->regiontype == RGN_TYPE_HEADER) {
     prefsizey = ED_area_headersize();
   }
   else if (region->regiontype == RGN_TYPE_TOOL_HEADER) {
diff --git a/source/blender/editors/screen/screen_ops.cc b/source/blender/editors/screen/screen_ops.cc
index 47e1c459a65..13ebd6f725e 100644
--- a/source/blender/editors/screen/screen_ops.cc
+++ b/source/blender/editors/screen/screen_ops.cc
@@ -2871,7 +2871,7 @@ static int region_scale_modal(bContext *C, wmOperator *op, const wmEvent *event)
         else if (rmd->region->flag & RGN_FLAG_HIDDEN) {
           region_scale_toggle_hidden(C, rmd);
         }
-        else if (rmd->region->flag & RGN_FLAG_DYNAMIC_SIZE) {
+        else if (rmd->region->flag & RGN_FLAG_NO_USER_RESIZE) {
           rmd->region->sizex = rmd->origval;
         }
       }
@@ -2913,7 +2913,7 @@ static int region_scale_modal(bContext *C, wmOperator *op, const wmEvent *event)
         else if (rmd->region->flag & RGN_FLAG_HIDDEN) {
           region_scale_toggle_hidden(C, rmd);
         }
-        else if (rmd->region->flag & RGN_FLAG_DYNAMIC_SIZE) {
+        else if (rmd->region->flag & RGN_FLAG_NO_USER_RESIZE) {
           rmd->region->sizey = rmd->origval;
         }
       }
diff --git a/source/blender/editors/space_buttons/space_buttons.cc b/source/blender/editors/space_buttons/space_buttons.cc
index 4a83aeae3bf..6a5c5d4873b 100644
--- a/source/blender/editors/space_buttons/space_buttons.cc
+++ b/source/blender/editors/space_buttons/space_buttons.cc
@@ -593,7 +593,7 @@ static void buttons_header_region_message_subscribe(const wmRegionMessageSubscri
 
 static void buttons_navigation_bar_region_init(wmWindowManager *wm, ARegion *region)
 {
-  region->flag |= RGN_FLAG_PREFSIZE_OR_HIDDEN;
+  region->flag |= RGN_FLAG_NO_USER_RESIZE;
 
   ED_region_panels_init(wm, region);
   region->v2d.keepzoom |= V2D_LOCKZOOM_X | V2D_LOCKZOOM_Y;
diff --git a/source/blender/editors/space_file/space_file.cc b/source/blender/editors/space_file/space_file.cc
index c057779bebc..596f4b9d882 100644
--- a/source/blender/editors/space_file/space_file.cc
+++ b/source/blender/editors/space_file/space_file.cc
@@ -79,14 +79,14 @@ static SpaceLink *file_create(const ScrArea * /*area*/, const Scene * /*scene*/)
   BLI_addtail(&sfile->regionbase, region);
   region->regiontype = RGN_TYPE_UI;
   region->alignment = RGN_ALIGN_TOP;
-  region->flag = RGN_FLAG_DYNAMIC_SIZE;
+  region->flag = RGN_FLAG_DYNAMIC_SIZE | RGN_FLAG_NO_USER_RESIZE;
 
   /* execute region */
   region = static_cast<ARegion *>(MEM_callocN(sizeof(ARegion), "execute region for file"));
   BLI_addtail(&sfile->regionbase, region);
   region->regiontype = RGN_TYPE_EXECUTE;
   region->alignment = RGN_ALIGN_BOTTOM;
-  region->flag = RGN_FLAG_DYNAMIC_SIZE;
+  region->flag = RGN_FLAG_DYNAMIC_SIZE | RGN_FLAG_NO_USER_RESIZE;
 
   /* tools props region */
   region = static_cast<ARegion *>(MEM_callocN(sizeof(ARegion), "tool props for file"));
diff --git a/source/blender/editors/space_userpref/space_userpref.cc b/source/blender/editors/space_userpref/space_userpref.cc
index 49d7c30ae88..ae501e10724 100644
--- a/source/blender/editors/space_userpref/space_userpref.cc
+++ b/source/blender/editors/space_userpref/space_userpref.cc
@@ -66,7 +66,7 @@ static SpaceLink *userpref_create(const ScrArea *area, const Scene * /*scene*/)
   BLI_addtail(&spref->regionbase, region);
   region->regiontype = RGN_TYPE_EXECUTE;
   region->alignment = RGN_ALIGN_BOTTOM | RGN_SPLIT_PREV;
-  region->flag |= RGN_FLAG_DYNAMIC_SIZE;
+  region->flag |= RGN_FLAG_DYNAMIC_SIZE | RGN_FLAG_NO_USER_RESIZE;
 
   /* main region */
   region = static_cast<ARegion *>(MEM_callocN(sizeof(ARegion), "main region for userpref"));
diff --git a/source/blender/makesdna/DNA_screen_types.h b/source/blender/makesdna/DNA_screen_types.h
index cef47df1653..a7a2ee7e2a5 100644
--- a/source/blender/makesdna/DNA_screen_types.h
+++ b/source/blender/makesdna/DNA_screen_types.h
@@ -713,16 +713,13 @@ enum {
 enum {
   RGN_FLAG_HIDDEN = (1 << 0),
   RGN_FLAG_TOO_SMALL = (1 << 1),
-  /**
-   * Force delayed re-initialization of region size data, so that region size is calculated
-   * just big enough to show all its content (if enough space is available).
-   * Note that only ED_region_header supports this right now.
-   */
+  /** Enable dynamically changing the region size in the #ARegionType::layout() callback. */
   RGN_FLAG_DYNAMIC_SIZE = (1 << 2),
   /** Region data is NULL'd on read, never written. */
   RGN_FLAG_TEMP_REGIONDATA = (1 << 3),
-  /** The region must either use its prefsizex/y or be hidden. */
-  RGN_FLAG_PREFSIZE_OR_HIDDEN = (1 << 4),
+  /** Region resizing by the user is disabled, but the region edge can still be dragged to
+   * hide/unhide the region. */
+  RGN_FLAG_NO_USER_RESIZE = (1 << 4),
   /** Size has been clamped (floating regions only). */
   RGN_FLAG_SIZE_CLAMP_X = (1 << 5),
   RGN_FLAG_SIZE_CLAMP_Y = (1 << 6),