Swing has been the bane of my existence. At a previous company, we kept an entire team of un-fireable people who maintained the Java Swing client of our ancient desktop application. The code was littered with comments prophesying doom for anyone who would dare touch it. There were multiple magical invocations of static functions that did "initialization." The code had to compile under Java 6.

When I left that company, one of the places I interviewed was Liftoff. They asked what language I wanted for the pair-programming session. I chose Java.

They asked me to implement Tetris in Swing.