Moving the mouse after expanding the sidebar causes it to go back to original size

Steps to reproduce issue:
* Opened the example web app at emilk.github.io/eframe_template
* Drag the bar on the right side of the side panel further to the right, release the mouse
* Move your mouse

The side bar will shrink back to original size.

EDIT:

This happened on 2 computers in the browser, I also downloaded the source code, ran cargo run --release and the mac native compiled version does this as well. Really don't like this behavior.