This hack can be done without changing any documents.
insert the following in your style sheet(headerinclude):
.imgfix {width:expression(document.body.clientWidth -330)}
change the number "330" when the fixed images are still to large/small. (test this number with different screen resolutions)
create a vbcodetag [IMGFIX]
use this code replacement:
<img src="{param}" class=imgfix><br>
<a href="{param}">Click for full image</a><br>
to finish it, add an IMGFIX in your vbcodebuttons
See a demo at
http://www.crapforum.nl
Good luck.