As promised from here:
I have gone ahead and finished off implementing it, You can find the patch plus the necessary details here:
edulinux.homeunix.org/fvwm/patches.html
Note the caveat section. I will be addressing them very soon. I also make no apologies for the hideous mess of this patch. It’s not broken, but it contains a number of poor programming practices I will also be addressing,
For now consider it an alpha release. Have fun with it though. 
– Thomas Adam
Wonderful!
Worked very well!
Cool. Would be nice to post something to the Screenshots and Configs section. ;)
– Thomas Adam
I do not have title bar on windows. So the four corner is used to minimize, maximize, and close windows. This patch really helps because it pops up the hot corners as a visual indicator.
Screen shot (click for 1024x768) :
And the configure (not really any difference then your sample):
DestroyFunc DynColorSet
AddToFunc DynColorSet
+ I CleanupColorsets
+ I Colorset 16 fg white, bg $1, fgsh black
+ I Colorset 17 fg gray60, bg $0, fgsh gray30
+ I Style * HilightBorderColorsetRegions 16 16 16 16
+ I Style * BorderColorsetRegions 17 17 17 17
+ I Style * HilightHandlesColorsetRegions 3 2 3 2
+ I Style * BorderHandlesColorsetRegions 3 3 3 3Colorset 16 and 17 are dynamically created by sampling the background image.
Thomas, great job!
It looks like this patch has moved to xteddy.org/fvwm/patches.html.