Design question: Picking event source

[Matthias Kaeppler <nospam digitalraid com>]

Hi,

a question is bugging me, nearly since I started programming on my Gtk2 
filemanager. I hope you can help me resolving this issue, because it's 
also an important design question (I intend to publish the widget which 
is responsible for displaying/browsing directory contents, so I need its 
interface to be clean and easy).

The problem is this:
In the main window, I have two embedded components, which were 
programmed by myself. They are Gtk::ScrolledWindowS, which itself both 
embed a TreeView. Besides the scrollbars, those ScrolledWindow widgets 
are covered 100% by the TreeViewS. They merely act as a container.

The ScrolledWindowS are the components which ought to be used by the 
client, however, all user interaction besides scrolling takes place in 
the embedded TreeViewS.
This is a problem, because most events are fired by the TreeViewS, and 
not by the ScrolledWindowS, so the clients would have to connect their 
signal handlers to the underlying TreeView object, but I don't even want 
the client to know what exactly is working under the hood.

What I want is people connecting their signal handlers to the 
ScrolledWindow signals instead. However, this would mean (since those 
events are NOT fired by the ScrolledWindowS but by the TreeViewS), that 
I would have to catch the events fired by the TreeViewS first 
internally, and then delegate them to the composing ScrolledWindowS, 
which would fire them again, so the client gets notice of them.

However, this looks like an expensive abstraction, because I have at 
least one more function call for each event fired.

Is there a more elgant solution to achieve what I want?

Best regards,
Matthias

--
Matthias Kaeppler