Mine goes like this...first window opens but does not say custom, but if I click to change the gradient another window opens, and I can click on a new gradient and adjust it as I want.

I still get:
Satin Warning
Error while executing script-fu-layer-effects-satin:
Error: (<unknown> : 41852760) eval: unbound variable: math-ceil

Graechan, I deleted old version and installed new version just now of the ICCII and it still crashes as soon as I click custom gradient. Very strange

I installed to try. The new is nice...and no crashes at all for me...but Satin warning. The selection box around the text seems to cut the filter funny to me.
That could certainly be just me not doing things right, perhaps.

Very cool gramg...Nice to see yours working out okay.

Graechan, additional info from my side:
it seems that in my environment there is a lot of predefined functions used by "satin" which are not in (downloaded and installed your last version of the script);
the missing (for me) functions are:
-(define (math-round input)
-(define (math-ceil input)
-(define (add-over-layer img newlayer oldlayer)
-(define (add-under-layer img newlayer oldlayer)
-(define (draw-blurshape img drawable size initgrowth sel invert)
-(define (get-layer-pos img layer)
walking through google I found those definitions and copied them just before the "(define (script-fu-layer-effects-satin img...."
eventually I did receive no other "unbound variable" message;
still I get a problem, the stmt "(set! satinlayer (car (gimp-image-merge-down img satinmask 0)))" gives an error, I had to comment it out to have finally the script go to an end.
What's wrong in my environment? Is there somewhere another script which has the missing definitions and which I should have?
Many thanks...

I got the same errors...
They refer to functions, that are not available.
"math-round" can be changed by "round".
"math-ceil" can be changed by "ceiling"
Both functions are offered by script-fu (scheme).
The others seem to refer to other script functions, but I do not have them.
So I deleted the script...

Graechan, this all seems like an awful lot of work

how about taking the Jon Stipe layerfx.scm and swapping your updated iccii Stroke with the existing
also adding your Vignette and Add Border function and you're done

that would give us the best of both worlds

really i dont think with Gimp there is something like Gradient and Color Overlay needed

what would be cool though if RobA's Chisel script could be added to the J. Stipe Bevel script

This is a library error libpangoft2-1.0-0.dll in Gimp 2.8.4. Just replace the files in the bin folder.
GIMP library for Windows 64-bit file attached below.

btw:The same problem is with the script Blended (File>Create>Logos>Blended) in Gimp 2.8.4