An interesting observation Joe, I tried it myself, with just 'OPEN' enabled, and after selecting a couple of pages of voices one after another, I was starting to think...positive thoughts, and then it jumped back out again, in fact twice in succession.
I'm still trying to decide what the difference is between those 2 voice button settings, as 'Open' would suggest you need to press again to select it, but that's not the case at all, I'm not seeing any behaviour difference when using those 2 button options...which is strange.
Those 2 voice catagory button options, you would think that if set to 'OPEN' it would'nt switch voice until pressed again, but it does.
IOW if set to 'OPEN' in theory you would need to press twice, 1 to open it and a 2nd press to select it.
I did notice that this issue of jumping back out, also occurs if I'm browsing a pen-drive full of Midi files, where say one midi is playing, and you press a second midi, and it highlights it with the word 'Next' as normal and then a second press starts to play the new midi file, well just occasionally it will jump out to the 'Live Control Screen'.
I'll do further experimentation today, putting this button issue one side for a moment... I'm struggling to see any difference in actual use between these 2 category button options...ie. 'OPEN' and 'OPEN/SELECT' which is very strange as one would think there would be a distinct difference in how they worked when you selected voices, or am I missing something here, and I've not woke up yet...lol
Anyway Joe, it's certainly an interesting find, as I certainly never noticed it, now I need to find out exactly what it does...lol
With it set to 'Open' are you seeing any difference in how the buttons work ? do you now have to press twice to make a change ? or does it still function as before, as I don't seem to be seeing any difference at all....weird.
EDIT:
One thing is definite on mine anyway, if I press on that high point of the buttons it always works okay 'every-time', but if press the buttons anywhere else and it will frequently exit back to main screen. I just pressed the buttons 80 times using the hight point and it never missed once or bounced me back to the main screen, but it just bounced me back to main screen on the 5th press when pressed in the centre. So the workaround also seems to vary a little between boards it seems.
I'll have a read of the manuals to see what it has to say about those to 2 voice category button options, as I'm not seeing any difference at all whichever one I set it for.
Cameron