There are a few operating systems out there where hitting the maximise button doesn’t enlarge a window to cover the entire screen. Instead, it maximises to what the application actually needs. If it only needs 1024x768, that is exactly what it will get.
I use 2 monitors at work with an OS which doesn’t follow the above mentioned rule (yes, its Windows), and what I really hate is windows, message boxes and popups which jump into the middle of the desktop, which is usually inbetween the 2 monitors. It drives me nuts to no end. Microsoft applications are every bit as guilty as almost all other apps.