So, in checking whether macros still worked, I came across a crash.
The good news: crash is not the Instant Preview's cache's fault.
{F41359} < This crashes due to the brush being modified before recording, and thus playback crashes.
{F41363} < Here's the backtrace, must be an old crash proly.
{F41360} < This one works... sorta.
{F41361} < This is the funny result that I get from playback of the working macro.
I don't think anyone actually uses macros, so technically we could just disable the plug-in for 3.0 release if necessary. It needs redefinition anyway. (Like what problems we want it to solve, how it should be edited, etc.)