XfceAboutDialog missing getter and setter

[Benedikt Meurer]

Jeff Franks wrote:
> Benny,

Hey Jeff,

> There is no getter and setter for the XfceAboutDialog icon property. 
> Since xfce_about_dialog_new_empty() creates an empty about dialog there 
> should be.

I talked to Jasper about this some time ago already: Gtk now offers
GtkAboutDialog, so from my point of view it makes sense to turn
XfceAboutDialog into a simple wrapper to GtkAboutDialog (we can do that
without breaking the API/ABI). If nobody complains I'll do that before
Xfce 4.4.

> Also I notice that xfce_about_dialog_new_with_values() does 
> not call g_object_ref() to reference the icon but 
> xfce_about_dialog_finalize() calls g_object_unref() to unreference the icon.

That's indeed a bug, which also explains a weird crash in Terminal. It's
fixed now.

> Jeff.

Benedikt