emacs-30 11e7ae3964e: Fix bug#72254

[Po Lu]

branch: emacs-30
commit 11e7ae3964e192b0e4bcc437a04278ee727e720b
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix bug#72254
    
    * src/pgtkselect.c (Fpgtk_get_selection_internal): If requesting
    TARGETS with just one result, return it as a vector.
    (bug#72254)
---
 src/pgtkselect.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/src/pgtkselect.c b/src/pgtkselect.c
index 271411b87ca..9e172c58602 100644
--- a/src/pgtkselect.c
+++ b/src/pgtkselect.c
@@ -1644,10 +1644,24 @@ frame's display, or the first available X display.  */)
 
   if (NILP (val) && FRAME_LIVE_P (f))
     {
-      Lisp_Object frame;
+      Lisp_Object frame, val;
       XSETFRAME (frame, f);
-      return pgtk_get_foreign_selection (selection_symbol, target_type,
-                                        time_stamp, frame);
+
+      val = pgtk_get_foreign_selection (selection_symbol, target_type,
+                                       time_stamp, frame);
+
+      /* A window property holding just one item is indistinguishable
+        from an array of one element, and is always decoded as the
+        former, producing issues with programs that expect the TARGETS
+        property always to return vectors, even when the toolkit
+        reports just one data type.  Though X sidesteps this ambiguity
+        by defining TARGETS as returning at least two properties
+        TARGETS and MULTIPLE, GTK knows no such scruples, and therefore
+        symbol values (or nil) should be enclosed in vectors when
+        TARGETS is being requested.  (bug#72254) */
+      if (EQ (target_type, QTARGETS) && (NILP (val) || SYMBOLP (val)))
+       val = make_vector (NILP (val) ? 0 : 1, val);
+      return val;
     }
 
   if (CONSP (val) && SYMBOLP (XCAR (val)))