OK. I have a very first version of the UM2 pause feature running on the UM1. It requires that firmware retraction is enabled, brings the 'M601' command with it and still has a small bug that the display is blank for some seconds. And it leads to underextrusion after resuming as the nozzle is still oozing a bit during the pause. This could be compensated with the additonal un-retraction length of the firmware retraction. Both bed and hotend are kept on temperature. The x/y/z-steppers are blocked for the predefined time (60s), the e-steppers are free.
Any comments so far?
If someone want's to play lab bunny, you're welcome (I would need your configuration.h and configuration_adv.h). But be warned, it's a B.R.A.T.P.-O.S. version... (yep, I just invented that abbreviation... it means BE READY AT THE POWER-OFF SWITCH).
edit: A well-known man at UM just reminded me that the switch filament option in Marlin (I think it's not switched on by default) does about the same what the UM2 pause feature does. So you may try this with the standard Marlin code from ErikZalm.
edit2: I managed to avoid that the steppers for x/y/z are released.