This is what an error looks like under GEM, in this case when you run out of disk space. Amazing that a 2000s era DOS program behaves better in the face of a lack of disk space than a 2020s Linux...

Programs of course still take over the entire screen when you run them, as with previous versions.

Here we can see several actual programs running at the same time.

An about screen for one of the running programs.

Finally, here is the printer output program.