Well we need to make a distinction between external apps (music players, gps software, and other car "control" / interface programs) and productivity applications and/or video playback applications (DVD Players, Internet Explorer, Word, Excel, Notepad, Autocad, ...). The former appear to be compliant with the law (I'm no lawyer though) while the latter are not. For your external application buttons, perhaps each one can have a configuration property that allows the user to specify if they should be 'locked out'. What do you think?