How to get caret position inside the active webforms designer having only the DTE object in VS2008?

Question

I want to know some information about where the caret is int the currently active webforms designer window, but I have only the DTE object of VS2008. Anything that gets close to this might help, but what I need is:

• know the EditableDesignerRegion that corresponds to the place where the carret is
• know the position of the carret in the text of that editable region (specifically if the caret is at the last possible position in that region)

These editable regions may or may not have WebControls inside them.