i would set it to something like RShift or anything else as LAlt and Tab is the key for changing your current tabs on windows.
Oh, I didn't know that. You can press that, get tabbed out real quick, and change your keybind then.
Also, alternatively you could do
RTB_Overlay::toggleOverlay(RTB_Overlay);in console to open the overlay and then set a keybind using the options.