Emacs mode for GDB - questions

[Nick Roberts]

I have updated the mode that I am writing for Emacs.
(http://www.nick.uklinux.net/gdbel-0.7.tgz). It acts as a GUI for gdb and I
have reported it previously on this mailing list.

The main feature that I have added is machine code level debugging. Breakpoints
can be set at addresses and icons are displayed. The relevant buffer follows
the frame but there is no overlay arrow to point to the current line as emacs
can only have one overlay arrow and that is used by the source buffer.

I have the following questions :

1) I don't know if this is an important feature now that compilers are much more
efficient. Do people debug at this level in an Emacs environment ?

2) Is it possible to change Emacs to have more than one overlay arrow 
(buffer-local) ? Would this be difficult ?

3) If only one overlay arrow is possible, would the display margin be a good
place to mark the current line ?

Nick