Allow dragging and dropping multiple actions

* doc/lispref/frames.texi (Drag and Drop): Document new meaning
of `action'.
* lisp/term/haiku-win.el (x-begin-drag): Correct for new meaning
of `action'.
* src/xfns.c (Fx_begin_drag): Handle new alist meaning of
`action'.
* src/xterm.c (x_dnd_begin_drag_and_drop): New parameters
`ask_action_list', `ask_action_names' and `n_ask_actions'.
* src/xterm.h: Update prototypes.

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/term/haiku-win.el b/lisp/term/haiku-win.el
index 8ec959a7584..1433620875b 100644
--- a/lisp/term/haiku-win.el
+++ b/lisp/term/haiku-win.el
@@ -224,7 +224,9 @@ take effect on menu items until the menu bar is updated again."
               (push (cadr selection-result)
                     (cdr (alist-get (car selection-result) message
                                     nil nil #'equal))))))))
-    (prog1 (or action 'XdndActionCopy)
+    (prog1 (or (and (symbolp action)
+                    action)
+               'XdndActionCopy)
       (haiku-drag-message (or frame (selected-frame))
                           message))))