Yes, there is a way to change the mb3 options.
I've done this before a year and I can tell you there is enough information in the help files. The menu file is located in <install dir>\UGII\menus and the file's name is ug_view_popup.men. You can open it with any text editor you like. For the syntax please review the documentation.
I hope this helped.
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"...standards are great because they give nonconformists something to not conform to..."
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Penkov, Peter I.
Non-standard Equipment Designer
The 'out of the box' bitmaps are hard-coded into the software & you cannot access them directly. However, you can copy them using screen capture/print screen & then paste them into an image editing or icon making software.