2 files changed, 9 insertions, 0 deletions
diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index adb2e0e3b23..286cb1571bd 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -893,6 +893,12 @@ bool UI_but_active_only_ex(
     }
   }
   if ((activate == true) || (found == false)) {
+    /* There might still be another active button. */
+    uiBut *old_active = ui_region_find_active_but(region);
+    if (old_active) {
+      ui_but_active_free(C, old_active);
+    }
+
     ui_but_activate_event((bContext *)C, region, but);
   }
   else if ((found == true) && (isactive == false)) {
diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 21cadec0d5f..bcb4f7c672f 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -8001,6 +8001,9 @@ static void button_activate_init(bContext *C,
 {
   uiHandleButtonData *data;
 
+  /* Only ever one active button! */
+  BLI_assert(ui_region_find_active_but(region) == NULL);
+
   /* setup struct */
   data = MEM_callocN(sizeof(uiHandleButtonData), "uiHandleButtonData");
   data->wm = CTX_wm_manager(C);