When using midi clips, and specifying a program change in one of the clips, the back to arrangement button will always light up. however, this seems to be a false positive, as hitting this button doesn't change the actually content of the arrangement, only the settings in the vst/i parameters, which if selecting this option during playback will actually change the sound of the arrangement.
I am only bringing this up because it seems to be inaccurate notification... when I personally see this light up my instict is to press it again to revert to the 'original' data, especially when I cannot remember what I might have changed.
Perhaps the back to arrangement button shouldn't light up in certain situations.
Greg