It affects both Windowed and full screen.
If you press and hold Alt and then Tab then it will alt-tab out of the program, upon returning to the program you can observe the behavior by pausing the game and accessing a menu option like configuring the controls or a confirmation box like when quitting the program.
If you press and hold Tab and then press Alt however, it will not alt-tab out of the program but it will still exhibit Tab being stuck and menu items rapidly being cycled through as though Tab was held down.
