Highly recommend you find his youtube video on how to properly use this as I didn't find it very intuitive the first time. But this works great for large monitors where you don't want to share the whole screen but also don't want to share just a single app/window!

This app would be infinitely more useful if it simply drew a boarder to show what portion of the screen was being shared. Right now it’s invisible and you have to keep the preview window up which takes up valuable space and is very distracting. As it stands, great idea but the execution makes it useless.

if I click on the menu bar->reframe and move the frame into my secondary monitor, the dotted lines dissapear and the mac becomes unusable, all the content seems to have an overlay on top of it, doesn't let you click on anything, had to restart forcefully.