Oh, OK, so a Shape widget, like something you drew with the Pen? Yes, same deal… all interactive areas are rectangular, just like straight HTML. You’re hitting the dreaded “rectangular hotspot” issue, which is common to many graphics systems. There are several solutions to this in HTML/CSS, such as defining imagemaps or using CSS sprites, but none I’ve seen applied to Axure (yet.) In theory, these could be implemented in Axure via javascript or CSS injection (or the plugins on AxureShare.)
Here are a few starting points if you want to pursue this:
https://forum.axure.com/t/clickable-area-of-widgets-and-bounding-box/36072?u=mbc66