I'd been using Shutter to do screen captures from selected portions of the screen. The usual method is to use the mouse to draw a rectangle,then press ENTER to grab that selection. The first part works -- I can select a portion of the screen -- but the ENTER is ignored. I have to use CTRL-ALT-F2 to open a console and kill the shutter process to get control of the Gnome Shell again.
https://bugzilla.redhat.com/show_bug.cgi?id=708433