Or you can do this... Go to you MacroQuest.ini file. (Using your favorite Edit program) and go to these lines:
# setting CycleNextWindow=0 disables it.
CycleNextWindow=` (enter a key that you want to use to switch screens after the =) (I use the tilda as my key)
# setting CyclePrevWindow=0 disables it.
CyclePrevWindow=ctrl+` (you can use two keys as well but you need to add a + between the two keys)
Save the file and then when you hit that key in game it will switch to the next screen or the previous one depending on which key you press.