a gtk.Widget which should be a drag destination for palette
the flags that specify what actions GTK+ should take for drops on that widget
the GtkToolPaletteDragTargets which the widget should support
the GdkDragActions which the widget should suppport
2.20
Sets palette as drag source (see ToolPalette.setDragSource) and sets widget as a drag destination for drags from palette. See gtk_drag_dest_set().