I've just downloaded the new Irdia today for the first time, and I'm trying it out. One thing I've noticed is that if the Alloy theme is ever used during a run of IDEA, I cannot fully maximize the window. A maximize makes the window very large, but the window frame still exists and there is a pixel border on the botton of the window where the desktop shows through -- in order words the window is very large but not quite maximized.
When using the old IDEA 4.5 theme, and only ever that theme, maximize and restore work properly. I have a dual monitor system (both monitors are 1280x1024) on an Intel card. IDEA is being displayed on the primary monitor, and there is no start bar on that monitor.