Likely this bug has existed for much longer than just 4.16. I saw numerous reports with people unable to determine the cause. I found the cause and I hope I don’t get a crap response like they did. Anyway, here goes:
Sometimes the editor bugs out with mouse focus when using the BP graphs. Any graph window will bug out (UMG, Actor, Material, etc). It seems to occur (at least one way) by using a custom quit game event from a UMG widget. If you use an “On Pressed” event to fire the “Quit Game” function the PIE window does not return mouse control to the editor correctly resulting in some odd behavior. If you instead use “On Released” it doesn’t happen.
In the images with the selection box, it looks like the mouse thinks the focus is on the first node in the BP graph, but since I don’t really understand how the BP graph implementation works, I can’t say 100% that is the case.
Thanks for taking the time to read, hope this solves some people’s issues. Again, I doubt this is the only
way this bug occurs, but it is totally reproducible.
