Returns the clipboard object for the given selection to be used with this.
this must have a Display associated with it, so must be attached to a toplevel window.
a Atom which identifies the clipboard to use. gdk_selection_clipboard gives the default clipboard. Another common value is gdk_selection_primary , which gives the primary X selection.
the appropriate clipboard object. If no clipboard already exists, a new one will be created. Once a clipboard object has been created, it is persistent for all time.