plazmaplanna: when I press f11 while in the game it doesn't do anything?
There are 2 shortcuts for the game, one to the normal version, and the other the Developer Mode version with the cheat window enabled (this version has a red text warning on the left side of the main menu screen).
IIRC the GOG installer just puts a shortcut for the normal version on the desktop, the other should be in the start menu folder for the game. You can also start it directly from the install folder, or create your own shortcut (..\Divinity II - Developers Cut\Bin folder - Divinity2.exe is the normal mode, Divinity2-Debug.exe has the Developer Mode enabled).