Fwumpy
Yo,
You could try something like this..
Aslong you are not using Scrollto or camera behaviors on your player and don't want your layout to scroll beyond the viewport...
System> Compare two values
> Player1.Y > 'viewportBottom'
>> set player.y to viewportBottom
--------
System> Compare two values
> Player1.Y < 'viewportTop'
>> set player.y to viewportTop
--------
System> Compare two values
> Player1.X < 'viewportLeft'
>> set player.y to viewportLeft
--------
System> Compare two values
> Player1.X > 'viewportRight'
>> set player.X to viewportRight
** edit, You might want to add +/- pixels to each set X/Y, so that it stays inside the viewport and not halfway out.. ie, if your player is 100 pixels wide then set player.X to "viewportRight+50" etc.
hope it helps