In my german installation, after hitting compile, press Alt+Space directly followed by (as Justus mentioned, it can happend that when the compile is finished, that the complied window will go to the background) v (in german for Verschieben (Move), so this my be a different key in a installation for a different country, you can check e.g. in the notepad which key to use) followed by one of the directional arrows on the keyboard, then wait for the compile to be finished, you will then (and not before) be able to move your compile window with your mouse (until you left click).