GtkLabel substring support

[Brian Cameron <Brian Cameron sun com>]

Havoc:

> Havoc Pennington <hp redhat com> writes: 
> > Should probably add an API to get the selection start/end offset,
> > along the lines of the GtkEntry API.
> > 
> 
> I just checked this in.

Thanks much!  It would also be useful if GtkLabel had a function
for returning a substring of the text, like gtk_editable_get_chars
in GtkEntry or gtk_text_buffer_get_text in GtkTextView.  These
functions allow you to pass in the start offset & end offset and
return the text between these offset points.

I can certainly implement such functions myself by just using
get_label_get_text and doing the work myself, but it seems like
it would be a useful general purpose function for GtkLabel to
support.

Brian