Do you know how to synchronize selection in a Visio Viewer and in a Grid control placed on custom UI form? The task is to change selected row when selected form in the Viewer is changed and vice versa.
There is no simple way - if there is a way, it would require a lot of trial/error code. One idea could be to trigger a change to a user-defined cell (that is mapped to a property) each time the shape is selected. This could technically cause RS-Visio integration to update the property and in this property's whenchanged, you could change the 'Selected Index' of the grid.