We should be able to move, Zoom in/out, Pan the Mlti-layout sheets.....It is annoying when it snaps out of screen. I guess it is possible in the next release....then press the exit icon to get out of the "sheet layout"
Unfortunately, you cannot pan in MSP (as you noticed) -- but you can reselect any Detail that has already been named, either by clicking on the menu button or hitting the appropriate Function key. If it has not been named yet, then it is not saved, so you just have to insert it again.
....as a sort of work around, you can do a print-preview then pan and zoom on that sheet - and it's only one extra mouse click from the MSP layout....you can also use the keyboard arrow keys to navigate around the plot drawing.
