i'm not trying to rain on your parade or anything -- this is simply an issue i was dealing with myself when trying to make a custom shader, and was curious about a more experienced insight. your shader is still useful and a good example that will probably help me in trying to make my own custom shaders.
Well I was only able to use the existing offset commands, I don't know what restrictions are there. I'm looking at it right now however.
To make sure I understand you, is it always 32 pixels? I ask because from trying it out myself it seemed to work right with the exception of the shrinking.
unless i stretch the image in the layout editor, yes. i'll grab a screenshot. i'm noticing a difference in what's displayed on the layout editor and runtime, also -- so perhaps there's a bug afoot (my hardware is modern and up to date).
edit: <img src="http://upload.dfyb.net/uploaded/32pixels_sadface.png">
shown here is 124,124 offset. the darker green square is 32,32