Qt grabs all mouse input

Basically what happens is that at some point Qt apps catch all mouse input and then ignore it (also affects all other running applications, even non-Qt ones). Only way to temporarily fix this is to exit application (via <Alt>+<F4>) and restart it.
I do not know what triggers it. I observed this behavior in Qt Creator 4.1.0 (uses Qt 5.7.1), PuddleTag 1.2.0 (uses Qt 4.8.7) and also sometimes after compiling and running my Qt apps via Qt Creator.