Is there any way to anchor a popup to an element in an embedded SVG such as a path or rect element?
The anchor option can take a string with the id of the element it is “anchored to”. If you assign an id to the rect inside the svg, that same id should work for the popup.
$('#my-popup').mobiscroll().popup({
anchor: '#myRecID',
});
Then in your svg:
<svg>
<rect id="myRecID" x="10" y="10" width="100" height="50" />
</svg>