When do regressions become high priority for developers?

[Stefan Dösinger]

My personal priority are similar to Vincent's. If I cause a regression, I try 
to fix it

*) If its an easy fix, useful hints in the bug report etc, and my time permits
*) Or if the fix is important to the one who pays my electricity 
bills(CodeWeavers)
*) If the regression is a real regression because the patch had a flaw, and 
not because it happened to uncover existing other bugs(for example, I do NOT 
consider Bug 18401 a regression)
*) If the regression happens in an area of code that is generally shaky and 
needs more attention to fix. In that case just trying to patch out the 
regression will cause new regressions - directly working on the big fix as 
time permits is usually better.

There are surely some exceptions to this etc and I guess I left some easier 
regressions I caused untouched because I simply  lost track of them. Every 
now and then they get randomly fixed or someone else picks them up.