UI: show confirmation for metaball delete

Matches other modes.

release/scripts/startup/bl_ui/space_view3d.py

@@ -3407,7 +3407,9 @@ class VIEW3D_MT_edit_meta(Menu):
         layout.separator()
 
         layout.menu("VIEW3D_MT_edit_meta_showhide")
-        layout.operator("mball.delete_metaelems", text="Delete...")
+
+        layout.operator_context = 'EXEC_DEFAULT'
+        layout.operator("mball.delete_metaelems", text="Delete")
 
 
 class VIEW3D_MT_edit_meta_showhide(Menu):

source/blender/editors/metaball/mball_edit.c

@@ -508,6 +508,7 @@ void MBALL_OT_delete_metaelems(wmOperatorType *ot)
 	ot->idname = "MBALL_OT_delete_metaelems";
 
 	/* callback functions */
+	ot->invoke = WM_operator_confirm;
 	ot->exec = delete_metaelems_exec;
 	ot->poll = ED_operator_editmball;