Cooperative multitasking, like in #Windows 3, is messy. If your #Win16 app needed to do anything that takes a long time, it would need to divide the long-running task into chunks small enough that each one takes only a few tens of milliseconds. Between each chunk, it would need to save the state of the long-running task, return to Windows, and wait its turn to run the next chunk. I never wrote Win16 code myself, but that couldn't have been easy.

#retrocomputing