Use event location property.

notebooks/using_show_and_widgets.ipynb

@@ -511,7 +511,7 @@
     "from baukit import Textbox\n",
     "coord_b = Textbox()\n",
     "def handle_click(e):\n",
-    "    loc = e.target.event_location(e)\n",
+    "    loc = e.location\n",
     "    coord_b.value = f'x,y=({loc.x:.2f}, {loc.y:.2f}) inside={loc.inside}'\n",
     "pw.on('click', handle_click)\n",
     "show(show.TIGHT, [['Click the previous plot to see coordinates here:', coord_b]])"