[canucker2016]

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.