Fix #146284: Missing Navigation Bar in Preferences

Follow up to !146169

- Add versioning so the new sidebar shows up in old files.
- Remove the hidden flag so it shows up in new Preferences editors.
- Add "Sidebar" toggle to the View menu, and expose region toggle.

Pull Request: https://projects.blender.org/blender/blender/pulls/146321

scripts/startup/bl_ui/space_userpref.py

@@ -87,8 +87,12 @@ class USERPREF_MT_editor_menus(Menu):
 class USERPREF_MT_view(Menu):
     bl_label = "View"
 
-    def draw(self, _context):
+    def draw(self, context):
         layout = self.layout
+        view = context.space_data
+
+        layout.prop(view, "show_region_ui")
+        layout.separator()
 
         layout.menu("INFO_MT_area")
 

source/blender/blenkernel/BKE_blender_version.h

@@ -27,7 +27,7 @@
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 83
+#define BLENDER_FILE_SUBVERSION 84
 
 /* 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

source/blender/blenloader/intern/versioning_500.cc

@@ -3339,6 +3339,26 @@ void blo_do_versions_500(FileData *fd, Library * /*lib*/, Main *bmain)
     FOREACH_NODETREE_END;
   }
 
+  if (!MAIN_VERSION_FILE_ATLEAST(bmain, 500, 84)) {
+    /* Add sidebar to the preferences editor. */
+    LISTBASE_FOREACH (bScreen *, screen, &bmain->screens) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          if (sl->spacetype == SPACE_USERPREF) {
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
+            ARegion *new_sidebar = do_versions_add_region_if_not_found(
+                regionbase, RGN_TYPE_UI, "sidebar for preferences", RGN_TYPE_HEADER);
+            if (new_sidebar != nullptr) {
+              new_sidebar->alignment = RGN_ALIGN_LEFT;
+              new_sidebar->flag &= ~RGN_FLAG_HIDDEN;
+            }
+          }
+        }
+      }
+    }
+  }
+
   /**
    * Always bump subversion in BKE_blender_version.h when adding versioning
    * code here, and wrap it inside a MAIN_VERSION_FILE_ATLEAST check.

source/blender/editors/space_userpref/space_userpref.cc

@@ -53,6 +53,7 @@ static SpaceLink *userpref_create(const ScrArea *area, const Scene * /*scene*/)
   BLI_addtail(&spref->regionbase, region);
   region->regiontype = RGN_TYPE_UI;
   region->alignment = RGN_ALIGN_LEFT;
+  region->flag &= ~RGN_FLAG_HIDDEN;
 
   /* Use smaller size when opened in area like properties editor. */
   if (area->winx && area->winx < 3.0f * UI_NAVIGATION_REGION_WIDTH * UI_SCALE_FAC) {

source/blender/makesrna/intern/rna_space.cc

@@ -7708,6 +7708,8 @@ static void rna_def_space_userpref(BlenderRNA *brna)
   RNA_def_struct_sdna(srna, "SpaceUserPref");
   RNA_def_struct_ui_text(srna, "Space Preferences", "Blender preferences space data");
 
+  rna_def_space_generic_show_region_toggles(srna, (1 << RGN_TYPE_UI));
+
   prop = RNA_def_property(srna, "filter_type", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_sdna(prop, nullptr, "filter_type");
   RNA_def_property_enum_items(prop, filter_type_items);