Improve handling of fallback drop protocols

* lisp/x-dnd.el (x-dnd-use-offix-drop): New value `files', which
means to only drop files using the OffiX protocol.  Make it the
default.
(x-dnd-handle-old-kde): Handle other data types correctly.
(x-dnd-offix-old-kde-to-name): New variable.
(x-dnd-offix-id-to-name): Fix typo in doc string.
(x-dnd-handle-unsupported-drop): Implement new value.

1 files changed, 43 insertions, 12 deletions

diff --git a/lisp/x-dnd.el b/lisp/x-dnd.el
index aa4eb8849f9..3b15eb432e3 100644
--- a/lisp/x-dnd.el
+++ b/lisp/x-dnd.el
@@ -24,8 +24,9 @@
 
 ;;; Commentary:
 
-;; This file provides the drop part only.  Currently supported protocols
-;; are XDND, Motif and the old KDE 1.x protocol.
+;; This file provides the receiving side of the XDND and Motif
+;; protocols, and both the receiving and initiating ends of the old
+;; KDE (OffiX) and new OffiX protocols.
 
 ;;; Code:
 
@@ -103,14 +104,20 @@ The types are chosen in the order they appear in the list."
   :type '(repeat string)
   :group 'x)
 
-(defcustom x-dnd-use-offix-drop nil
+(defcustom x-dnd-use-offix-drop 'files
   "If non-nil, use the OffiX protocol to drop files and text.
 This allows dropping (via `dired-mouse-drag-files' or
 `mouse-drag-and-drop-region-cross-program') on some old Java
 applets and old KDE programs.  Turning this off allows dropping
-only text on some other programs such as xterm and urxvt."
+only text on some other programs such as xterm and urxvt.
+
+If the symbol `files', use the OffiX protocol when dropping
+files, and the fallback drop method (which is used with programs
+like xterm) for text."
   :version "29.1"
-  :type 'boolean
+  :type '(choice (const "Don't use the OffiX protocol for drag-and-drop")
+                 (const "Only use the OffiX protocol to drop files")
+                 (const "Use the OffiX protocol for both files and text"))
   :group 'x)
 
 ;; Internal variables
@@ -402,21 +409,43 @@ Currently XDND, Motif and old KDE 1.x protocols are recognized."
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;;  Old KDE protocol.  Only dropping of files.
+;;;  Old KDE protocol.
 
 (declare-function x-window-property "xfns.c"
 		  (prop &optional frame type source delete-p vector-ret-p))
 
-(defun x-dnd-handle-old-kde (_event frame window _message _format data)
-  "Open the files in a KDE 1.x drop."
+(defvar x-dnd-offix-old-kde-to-name '((-1 . DndTypeInvalid)
+                                      (0 . DndTypeUnknown)
+                                      (1 . DndTypeRawData)
+                                      (2 . DndTypeFile)
+                                      (3 . DndTypeFiles)
+                                      (4 . DndTypeText)
+                                      (5 . DndTypeDir)
+                                      (6 . DndTypeLink)
+                                      (7 . DndTypeExe)
+                                      (8 . DndTypeUrl))
+  "Alist of old KDE data types to their names.")
+
+(defun x-dnd-handle-old-kde (event frame window _message _format data)
+  "Handle an old KDE (OffiX) drop.
+EVENT, FRAME, WINDOW and DATA mean the same thing they do in
+`x-dnd-handle-offix.'"
   (let ((proto (aref data 4)))
     ;; If PROTO > 0, this is an old KDE drop emulated by a program
     ;; supporting a newer version of the OffiX protocol, so we should
     ;; wait for the corresponding modern event instead.
     (when (zerop proto)
-      (let ((values (x-window-property "DndSelection" frame nil 0 t)))
-        (x-dnd-handle-uri-list window 'private
-			       (replace-regexp-in-string "\0$" "" values))))))
+      (let ((type (cdr (assq (aref data 0) x-dnd-offix-old-kde-to-name)))
+            (data (x-window-property "DndSelection" frame nil 0 t)))
+        ;; First save state.
+        (x-dnd-save-state window nil nil (vector type) nil)
+        ;; Now call the test function to decide what action to perform.
+        (x-dnd-maybe-call-test-function window 'private)
+        (unwind-protect
+            (x-dnd-drop-data event frame window data
+                             (symbol-name type))
+          (x-dnd-forget-drop window))))))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;; New OffiX protocol.
 
@@ -432,7 +461,7 @@ Currently XDND, Motif and old KDE 1.x protocols are recognized."
                                  (8 . DndTypeUrl)
                                  (9 . DndTypeMime)
                                  (10 . DndTypePixmap))
-  "Alist of OffiX protocol types to their names.")
+  "Alist of OffiX data types to their names.")
 
 (defun x-dnd-handle-offix-file (window action string)
   "Convert OffiX file name to a regular file name.
@@ -1031,6 +1060,8 @@ WINDOW-ID is the X window the drop should happen to."
   (not (and (or (eq action 'XdndActionCopy)
                 (eq action 'XdndActionMove))
             (not (and x-dnd-use-offix-drop
+                      (or (not (eq x-dnd-use-offix-drop 'files))
+                          (member "FILE_NAME" targets))
                       (x-dnd-do-offix-drop targets x
                                            y frame window-id)))
             (or