alt Hacker NewsWell all they needed to do was erase the screen with white and draw on it, but their app's internal logic meant that they erased it more than once.
I was capturing QuickDraw library calls - the low level graphics primitives, to figure out where the graphics time in apps was going and found out sometimes excel did it 9 times
Of course users didn't see it more than once, but our hardware made all that wasted time run faster
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HansHamster • yesterday at 2:57 PM
Maybe their CRTs had horrible burn-in and they had to erase everything 9 times before it was gone...
It's more likely that one dev wrote the draw-cell code.
Another dev who's fixing a bug, realizes if they call a certain function either directly or indirectly, their particular bug gets fixed.
Oh, and as a side effect, the cell gets erased (again).
A few more fixes/new features added like this and the code is inadvertently erasing the same cell multiple times.
It takes a certain type of dev to step through in a debugger and Notice the app is doing way too much work and then to untangle the mess of code without causing regressions.