I’ve only tested this on OSX - But here’s a video
It’s on OSX 10.11.4. Projucer was just downloaded today, it’s 4.2.0, build date of April 6, 2016.
Note that in the video I’m only clicking on the items one time and it deselects them after a very brief period of time.
I looked around for a bug reporting place and didn’t find one, sorry if this is the wrong spot.
Edit: It’s actually really annoyingly everywhere within the application. For example, if I go to Tools > Global Preferences, it’s constantly bring the focus back to the main application. I can’t get something selected and changed within the 1/10th of a second I have before focus is drawn away from the active window.