Fei Min,
FWIW, you already can turn off any features that you don't need via
the config files (found in the fminit\configui folder) - this
includes standard menu items, context menus, keyboard shortcuts,
toolbar items, etc. For example, try the View > Menus > Quick option
and check out the GUI after that's applied.
The online manual "Customizing_Frame_products.pdf" describes how to
modify the GUI. Also, Shlomo Perets' ToolBarPlus Express available for
a nominal fee at http://www.microtype.com/resources.html, is an
excellent starting point to give you a customization environment.