Did you want the MS job? I mean, I could figure out how to make things overlap without repainting, and I'm a 4-year-old child.
That is, an IBM PC running at 4.77 MHz; with 128 KB of ram (or 640 KB if you're lucky). The OS would have been dos at something like version 2.x Some people[1] used Wordstar as their text editor.
You had limited multitasking -- TSRs maybe.
I'm not sure what programming language they used but possibly Microsoft C and assembly.
I don't know how it's handled these days, but when I was first playing around with Win32, you'd receive events telling you a region of your window was invalidated. You were expected to figure out what controls and images belonged in that region and just repaint those items because of the CPU load.