Comment by inigyou
10 hours ago
Before Windows Vista, Windows apps normally didn't have framebuffers. There was one framebuffer for the whole screen, and apps drew into it. That's why dragging another window over a non-responsive window left a "slime trail" - the non-responsive window wasn't redrawing parts of itself when the window covering them moved away.
Before Vista, we did not have window previews in task bar and alt+tab. We didn’t have a good multimedia framework based on the hardware codecs: media foundation arriving with Vista wasn’t a coincidence. It was hard to capture and encode desktop for screen recording and presentations: despite MS only added desktop duplication API in Win8, technically Vista and Win7 graphics stacks could already do that, MS just neglected. Also, these aero translucency visuals in Vista and Win7 were nice, until Win8 ruined everything.
All that stuff would be hard to impossible with the older GDI architecture and no desktop compositor process.