Selection in GtkTextBuffer

I’ve recently played around with GtkTextBuffer. It’s a rather nice text editing widget (or rather widget part). Unfortunately it misses one functionality, which is also missing from GtkEditable derived widgets: A signal for selection changes. There are two workarounds:

1. You can setup a notification on the “has-selection” property like this:

   buffer.connect("notify", on_buffer_notify)
   
   def on_buffer_notify(buffer, prop):
       if prop.name == "has-selection":
           if buffer.get_has_selection():
               ...
           else:
               ...
   

   This method only works if you are interested in whether there is a selection or not, not if you are interested in any selection changes. Also, this method works only for GtkTextBuffers, not for GtkEditables.

2. Tomboy uses a timeout to check the selection status:

   namespace Tomboy
   {
   	public class NoteWindow : ForcedPresentWindow 
   	{
                   ...
   		public NoteWindow (Note note) : 
   			base (note.Title) 
   		{
                           ...
   			// Sensitize the Link toolbar button on text selection
   			mark_set_timeout = new InterruptableTimeout();
   			mark_set_timeout.Timeout  = UpdateLinkButtonSensitivity;
                           ...
                   }
   
                   ...
   
   		void UpdateLinkButtonSensitivity (object sender, EventArgs args)
   		{
   			link_button.Sensitive = (note.Buffer.Selection != null);
   		}
   
                   ...
           }
   }
   

   This method works, but seems a bit complicated, when a simple signal should do the trick.

Filed as bug #448261.