Drag data has the following properties:
Drag action type (ie
Client specified arbitrary drag-and-drop type (a name and number pair).
Sent and received data format type.
Drag actions are quite obvious, they specify if the widget can
drag with the specified action(s),
gtk.gdk.ACTION_COPY would be a typical drag-and-drop
without the source data being deleted while
gtk.gdk.ACTION_MOVE would be just like
gtk.gdk.ACTION_COPY but the source data will be
'suggested' to be deleted after the received signal handler is called. There
are additional drag actions including
which you may want to look into when you get to more advanced levels of
The client specified arbitrary drag-and-drop type is much more flexible, because your application will be defining and checking for that specifically. You will need to set up your destination widgets to receive certain drag-and-drop types by specifying a name and/or number. It would be more reliable to use a name since another application may just happen to use the same number for an entirely different meaning.
Sent and received data format types (selection
target) come into play only in your request and received data
handler functions. The term selection target is
somewhat misleading. It is a term adapted from GTK+ selection (cut/copy and
paste). What selection target actually means is the
data's format type (i.e.
gtk.gdk.Atom, integer, or
string) that is being sent or received. Your request data handler function
needs to specify the type (selection target) of data
that it sends out and your received data handler needs to handle the type
(selection target) of data received.