Saving seleciton bound

[Aaron Borden <adborden live com>]

Hello,

I'm a developer on Tomboy, the simple note taking app on the GNOME
desktop. Some users would like the text selection in a note
(gtk_text_buffer) to be saved so that when the note is re-opened, the
selection bound and cursor are where the user last left them.

I've noticed that in GNOME you can't have two bodies of text selected at
the same time, even in different windows or different apps.
1. Open 2 windows of gedit
2. Type some text in window 1, highlight it.
3. Type some text in window 2, highlight it.

And the selection (highlight) disappears from window 1.

I'd like to change this behavior in Tomboy but the "mark-set" signal
doesn't have any information that can be used to determine whether the
selection bound was moved by the user working with the buffer or whether
it was moved from selecting text in another window. 

Any tips on how to approach this?

-Aaron