When your tablet needs a windowed UI, has it crossed some undrawn, implied boundary that makes it too complex for the kinds of casual tasks you'd want to accomplish on a tablet? Hard to say, but the mobile developers at Ixonos took to MWC last week to showcase a windowed build of Android on top of a tablet developed by Aava -- so at the very least, we know it's possible. The system is built atop Froyo and allows apps to continue running in the background -- they don't suspend, which means you can, say, play a video while you're off composing messages. The company also demonstrated the software on a dual-screen 7-inch tablet, allowing apps to be laun
