I can't speak to the MX-5000 and your STB, but I can provide you an example of how I would implement what your wanting to do with my remote control solution and STB. Perhaps the same thing would be possible with your remote and STB. Not sure. In my case I use a Pronto TSU9600 remote in conjunction with DIRECTV receivers, both of which support 2-way feedback over RS-232/IP. As such, using ProntoScript I would be able to invoke the keypad to be removed when receiving feedback from my DIRECTV receiver that the channel has changed. Easy enough to implement. Don't really see a way this could be done aside from using 2-way feedback.

That being said, I'd impress upon the customer the drawbacks of such functionality before implementing it for them. As KRAZYK states, what if the customer isn't finished with the keypad? What if they tune to the wrong channel by mistake? What if they tune to the right channel, but then decide to immediately tune to another channel instead for whatever reason? I would be extremely annoyed if the keypad went away every time the channel changed while I had it up. If the user is constantly making use of the keypad and it's a big deal for them to change to that page manually after entering the activity, then why not have it displayed as the primary page of the activity? After all, it's not like the hard buttons of the MX-5000 don't already provide for navigating the STB GUI and working the transport controls. What other essential functions are really left that some other page would need to take precedent, at least in the case of a user that's constantly hitting up the keypad? Would imagine as well that the available screen area should provide for enough room for both the keypad and the color buttons if they are used frequently as well.

Using if/else or "Press & Hold" you could of course maximize use of the hard buttons. Not sure which the MX-5000 supports. From what I understand some models don't support the traditional "Press & Hold", but can accomplish the same thing using if/else instead. Throughout the configuration file for my Pronto for instance I'll use a given hard button for multiple things based on the length of time the button is held and in some cases even execute an action after the given button is released as well. With my DIRECTV activity I've programmed the "Guide" hard button on a normal button press to bring up the programming guide. On a long button press (1 second or more) a short tone will sound from the remote then bringing up the list of DVR recordings instead. If the STB has a "LiveTV" function as many do which takes you to the front of the current tuner buffer you could always program one of the transport hard buttons on a long button press for that such as the "Play" button. To quickly access OnDemand content the "Menu" hard button could be programmed for that with a long button press. Just throwing some ideas out there for you per ways to limit use of the touch screen preventing the need for the user to leave the page containing the keypad.