Some end-user applications need to provide "minimize to tray" functionality. In order for the window manager to do the correct animation towards the status icon, the window that is to be minimized needs to have the _NET_WM_ICON_GEOMETRY hint set correctly (libwnck provides "wnck_window_set_icon_geometry"). This is currently not possible or only possibly by using direct calls to the X11 library (XChangeProperty).

I propose a new API function for GtkStatusIcon:

 gtk_status_icon_set_gtk_window_icon_geometry(GtkStatusIcon* i, GtkWindow* w);

This function should take the geometry of the GtkStatusIcon "i" and set the X11 WM hint _NET_WM_ICON_GEOMETRY so that a call to gtk_window_iconify() will have the window manager show a animation towards the GtkStatusIcon.

Currently, applications like Rhythmbox work with XChangeProperty (see e.g. "set_icon_geometry" in "rb-status-icon-plugin.c" in Rhythmbox's source code), and it's even more difficult if you want to have your application behave like this from PyGTK.