Fix findMenu y_ret: subtract top_width for content-relative coords

findMenu was returning y relative to the frame top (including titlebar).
getEntryAt expects y relative to the content area. Subtracting top_width
means pointer in titlebar gives y<0 → entry_no=-1 (no selection), which
is correct behavior matching the X11 path.

src/menu.c

@@ -1123,7 +1123,7 @@ static WMenu *findMenu(WScreen * scr, int *x_ret, int *y_ret)
 	    x >= (m)->frame_x && x < (m)->frame_x + MENUW(m) && \
 	    y >= (m)->frame_y && y < (m)->frame_y + MENUH(m)) { \
 		*x_ret = x - (m)->frame_x; \
-		*y_ret = y - (m)->frame_y; \
+		*y_ret = y - (m)->frame_y - (m)->frame->top_width; \
 		return (m); \
 	} \
 } while(0)