This is the most random collection of possible causes of an issue I had with IntelliJ and I’m completely unsure as to what actually caused the problem, but I’m writing about it anyway so that 1) I’ll remember how to fix it if I ever run across it again, and 2) on the off-chance that someone else actually does run into this problem, maybe this will help.
When using IntelliJ and IdeaVIM for Java development, I have a tab open for each of the Java source files I’m working with. I discovered that occasionally, when I flipped between tags in AwesomeWM (analogous to switching virtual desktops in most window managers), the top tab in IntelliJ would lose focus and I would be unable to type. The only resolution I could find when this problem occurs is to click another tab, then click back to the original tab, which would recapture focus and allow me to type again.
I remember having this problem before, a couple years ago, and I think the solution I had from before was to use Sun’s JDK instead of OpenJDK. However, Ubuntu doesn’t provide Sun’s JDK anymore by default, so instead I tried upgrading from OpenJDK 1.6 to OpenJDK 1.7. After upgrading both the JDK and JRE to 1.7, and restarting IntelliJ, the problems went away.
I still have no idea what exactly happened, but I’m glad that my problems went away, and hopefully someone else will find this useful. If someone actually knows what’s going on, please let me know in the comments.