bugfix [#20944] bad use of wm.invoke_popup(self) is crashing Blender

source/blender/editors/interface/interface.c

@@ -372,12 +372,16 @@ static void ui_popup_bounds_block(const bContext *C, uiBlock *block, int bounds_
 	/* and we adjust the position to fit within window */
 	width= block->maxx - block->minx;
 	height= block->maxy - block->miny;
+    
+    /* avoid divide by zero below, caused by calling with no UI, but better not crash */
+    oldwidth= oldwidth > 0 ? oldwidth : MAX2(1, width);
+    oldheight= oldheight > 0 ? oldheight : MAX2(1, height);
 
 	/* offset block based on mouse position, user offset is scaled
 	   along in case we resized the block in ui_text_bounds_block */
 	startx= window->eventstate->x + block->minx + (block->mx*width)/oldwidth;
 	starty= window->eventstate->y + block->miny + (block->my*height)/oldheight;
-	
+
 	if(startx<10)
 		startx= 10;
 	if(starty<10)