Still haven't cracked the SHP recompression code; but I'm close to cracking the SPHeader fix code.
As requested, you can double click on the location to get into the gross area of where you want your new centroid to be; and then use the +/- buttons to dial in the exact location.
The "write header to all icons" is for when you have a massive collection of 40 x P-51 mustang icons in that SHP and they all have the same basic centroid.
EDIT: Further work will have to wait for later; everything here so far is a proof of concept working on a massively kludged system; I have to go back and refactor more code to make storing/editing the new header data easier and actually doable.
