When switching computer from dual screen setup to single screen and opening iReport Designer - it will open window based on coordinates saved from dual screen setup and can sometimes show itself or query window outside of boundaries of single screen.
It looks very confusing to the user - like iReport Designer is hanging.
The fix would be to check if coordinates used are still valid for current screen configuration and adjust accordingly.
I found people reporting same problem here: http://community.jaspersoft.com/ireport-designer/issues/5118
After a very clever piece of detective work, a colleague of mine has solved this problem. By examining both the iReport source code and configuration files, he realised that the coordinates for the query window were actually outside of the active window - ie the query window *was* actually popping up when the button was clicked, but it was being painted off-screen, where it couldn't be seen or manipulated.
This was because I'd been using a dual-screen setup at home, then hibernated my laptop, then resumed it with just a single screen, and then opened the query window.
THIS IS A SERIOUS BUG IN iREPORTS! If the last location of the query window was off-screen, then iReports should ensure that those screen coordinates are still valid before opening the query window (and effectively freezing iReport).
It sounds like this bug is inherited from netbeans: https://netbeans.org/bugzilla/show_bug.cgi?id=164529
So not sure if JasperSoft can do anything about it.