Fix issues unregistering overridden panels

Previously overridden scene panels were removed but original panels were not restored.
Also added condition check for Blender version to generate list of panels to override, so we won't miss any errors using `try - except`.

src/blenderbim/blenderbim/bim/__init__.py

@@ -181,6 +181,7 @@ addon_keymaps = []
 icons = None
 is_registering = False
 last_commit_hash = "8888888"
+overridden_scene_panels = dict()
 
 
 def on_register(scene):
@@ -285,22 +286,7 @@ def unregister():
             km.keymap_items.remove(kmi)
     addon_keymaps.clear()
 
-    for panel in [
+    for original_panel, override_panel in tuple(overridden_scene_panels.items()):
-        "SCENE_PT_scene",
+        bpy.utils.unregister_class(override_panel)
-        "SCENE_PT_unit",
+        bpy.utils.register_class(original_panel)
-        "SCENE_PT_physics",
+        del overridden_scene_panels[original_panel]
-        "SCENE_PT_rigid_body_world",
-        "SCENE_PT_audio",
-        "SCENE_PT_keying_sets",
-        "SCENE_PT_simulation",
-        "SCENE_PT_custom_props",  # 4.0
-        # after SCENE_PT_keying_sets
-        "SCENE_PT_keying_set_paths" "SCENE_PT_keyframing_settings",
-    ]:
-        try:
-            bpy.utils.unregister_class(getattr(handler, f"Override_{panel}"))
-        except:
-            # NOTE: breaks Blender UI on unregister
-            # since default Blender panels are unregistered on load_post
-            # unregistering our override panels removes them from Blender completely
-            pass

src/blenderbim/blenderbim/bim/handler.py

@@ -21,6 +21,7 @@ import bpy
 import json
 import addon_utils
 import ifcopenshell.api.owner.settings
+import blenderbim.bim
 import blenderbim.tool as tool
 import blenderbim.core.owner as core_owner
 from bpy.app.handlers import persistent
@@ -259,9 +260,7 @@ def poll_check_blender_tab(cls, context):
 
 
 def get_override_scene_panel(panel_name):
-    original_panel = getattr(bpy.types, panel_name, None)
+    original_panel = getattr(bpy.types, panel_name)
-    if original_panel is None:
-        return
 
     override_panel = type(f"Override_{panel_name}", (original_panel,), {})
     override_panel.bl_idname = f"{panel_name}_override"
@@ -287,6 +286,22 @@ def get_override_scene_panel(panel_name):
     return override_panel
 
 
+OVERRIDE_SCENE_PANELS = (
+    "SCENE_PT_scene",
+    "SCENE_PT_unit",
+    "SCENE_PT_physics",
+    "SCENE_PT_rigid_body_world",
+    "SCENE_PT_audio",
+    "SCENE_PT_keying_sets",
+    "SCENE_PT_custom_props",
+    # after SCENE_PT_keying_sets
+    "SCENE_PT_keying_set_paths",
+    "SCENE_PT_keyframing_settings",
+)
+if bpy.app.version >= (4, 0):
+    OVERRIDE_SCENE_PANELS += ("SCENE_PT_simulation",)
+
+
 @persistent
 def load_post(scene):
     global global_subscription_owner
@@ -325,28 +340,14 @@ def load_post(scene):
         # To improve usability for new users, we hijack the scene properties
         # tab. We override default scene properties panels with our own poll
         # to hide them unless the user has chosen to view Blender properties.
-        for panel in [
+        for panel in OVERRIDE_SCENE_PANELS:
-            "SCENE_PT_scene",
+            override_panel = get_override_scene_panel(panel)
-            "SCENE_PT_unit",
+            if override_panel is None:
-            "SCENE_PT_physics",
+                continue
-            "SCENE_PT_rigid_body_world",
+            original_panel = getattr(bpy.types, panel)
-            "SCENE_PT_audio",
+            bpy.utils.register_class(override_panel)
-            "SCENE_PT_keying_sets",
+            bpy.utils.unregister_class(original_panel)
-            "SCENE_PT_simulation",  # 4.0+
+            blenderbim.bim.overridden_scene_panels[original_panel] = override_panel
-            "SCENE_PT_custom_props",
-            # after SCENE_PT_keying_sets
-            "SCENE_PT_keying_set_paths",
-            "SCENE_PT_keyframing_settings",
-        ]:
-            try:
-                override_panel = get_override_scene_panel(panel)
-                if override_panel is None:
-                    continue
-                original_panel = getattr(bpy.types, panel)
-                bpy.utils.register_class(override_panel)
-                bpy.utils.unregister_class(original_panel)
-            except Exception:  # some panels belong to different Blender versions
-                pass
     # https://blender.stackexchange.com/questions/140644/how-can-make-the-state-of-a-boolean-property-relative-to-the-3d-view-area
     for screen in bpy.data.screens:
         if len(screen.BIMAreaProperties) == 20: