Designates an image handle as returned by nvgCreateImage*() as the themes' icon sheet. The icon sheet format must be compatible to Blender 2.6's icon sheet; the order of icons does not matter.
A valid icon sheet is e.g. shown at http://wiki.blender.org/index.php/Dev:2.5/Doc/How_to/Add_an_icon
The D Programming Language's Unofficial Docs
beta
Designates an image handle as returned by nvgCreateImage*() as the themes' icon sheet. The icon sheet format must be compatible to Blender 2.6's icon sheet; the order of icons does not matter.
A valid icon sheet is e.g. shown at http://wiki.blender.org/index.php/Dev:2.5/Doc/How_to/Add_an_icon