Fix T65999: Crash when disabling an addon while its panel is visible

Note, the performance of the tests we run here is still bad since we have plenty
of panels around. But better than the crash.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D5116

1 files changed, 18 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_ui.c b/source/blender/makesrna/intern/rna_ui.c
index 1e5f1dc20ec..a2339a815dc 100644
--- a/source/blender/makesrna/intern/rna_ui.c
+++ b/source/blender/makesrna/intern/rna_ui.c
@@ -180,7 +180,7 @@ static void panel_draw_header_preset(const bContext *C, Panel *pnl)
   RNA_parameter_list_free(&list);
 }
 
-static void rna_Panel_unregister(Main *UNUSED(bmain), StructRNA *type)
+static void rna_Panel_unregister(Main *bmain, StructRNA *type)
 {
   ARegionType *art;
   PanelType *pt = RNA_struct_blender_type_get(type);
@@ -210,6 +210,23 @@ static void rna_Panel_unregister(Main *UNUSED(bmain), StructRNA *type)
   BLI_freelistN(&pt->children);
   BLI_freelinkN(&art->paneltypes, pt);
 
+  for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+    for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
+      for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+        for (ARegion *region = regionbase->first; region; region = region->next) {
+          if (region->type == art) {
+            for (Panel *pa = region->panels.first; pa; pa = pa->next) {
+              if (pa->type == pt) {
+                pa->type = NULL;
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
   /* update while blender is running */
   WM_main_add_notifier(NC_WINDOW, NULL);
 }