I have tried several approaches, and at the end the one that gave me the best results is BMP with MSK (mask files). It's more work than having a simple GIF or BMP or ICO, but you have more control over the final appearence.

>Is there a way to define a .DisabledPicture icon file in menu options such as in Command Buttons?, the problem is that I'm using now 256+ colors in my icons but when the option is disabled, the icon shows as a complete shadow. It works fine with icons having lots whites but not on more sophisticated icons.
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>Any advice, or workarounds?