[UPDATE] Brad Rhine has discontinued support for this module. However, I have hosted it here with his permission for the sake of archives.

Based on code provided by myself and Charles Yeomans, Brad Rhine has released the Toolbar Utilities module - a REALbasic module which adds most of the standard Mac OS X toolbar features to built-in REALbasic toolbars.

Developers looking to add features like toolbar display size and mode, toggle button visibility, and toolbar visibility to their toolbars without using the complicated HIToolbar code can use this module to do exactly that. However, customization still requires HIToolbar.