%bv (branch view) Functionality for Client that is Blind

I have a client that is blind and navigates our 200 GUI input windows of input data with speech software, which is JAWS by VFO (formerly Freedom Scientific). Some of the graphical controls, for example %ms (multiple selection box), we can change how to select items from 'CTRL, SHIFT, Mouse dragging' to 'arrow up and down with space bar or left-most click' which make it usable for him. We have a branch view control with a menu that will expand/collapse to edit our 200 GUI input windows. However, it can only be navigated with with left mouse click and double clicks. Is there any way to navigate the expandable/collapsible menus with keyboard strokes? If not, would it possible to add that feature. Thanks.

Please provide code for a short demo program that illustrates what you want.