Sorry for my late response, but there is actually a setting for this
Unfortunately it's not exposed to the settings menu... you can set it by opening the "config.properties" file in the game directory with a text editor and setting Game_RunInBackground to True, then save the file and launch the game again - now the game should no longer pause when losing focus.
Having said that, if it's just about plants, they will still continue to grow if the game lost focus
Ah! That is awesome, thank you! It's about the plants *and* the time. I like to just let the night pass while I do other things. It's good for my easily-distracted mind. I let it rest by doing things in RW during the day, then go back to work on other programs at night. By switching tasks like that I avoid fatigue!
Thanks for everyone else too for the workarounds, though!