get_icon

Gets the icon to be used for this.

Since there is no way to properly find the icon, a suboptimal heuristic is used to find it. The icon is the first icon found by looking at all the Application for each Window in this, then at all the Window in this. If no icon was found, a fallback icon is used.

Parameters:

this	a ClassGroup.

Returns:

the icon for this. The caller should reference the returned Pixbuf if it needs to keep the icon around.