Fix minor bugs with XDND support

* lisp/mouse.el (mouse-drag-and-drop-region): Report more
selection targets for the benefit of Qt and Mozilla.
* lisp/select.el (xselect--encode-string)
(selection-converter-alist): Add new selection targets.

* src/xterm.c (x_dnd_get_window_proxy): New function.
(x_dnd_get_target_window): New argument proto_out, and return
first window with XdndAware instead of bottommost window.
(handle_one_xevent): Use new argument `proto_out'.

1 files changed, 76 insertions, 40 deletions

diff --git a/src/xterm.c b/src/xterm.c
index d01d3e7cce3..83651376bfd 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -795,23 +795,21 @@ static struct frame *x_dnd_frame;
 
 #define X_DND_SUPPORTED_VERSION 5
 
+static int x_dnd_get_window_proto (struct x_display_info *, Window);
+static Window x_dnd_get_window_proxy (struct x_display_info *, Window);
+
 static Window
 x_dnd_get_target_window (struct x_display_info *dpyinfo,
-                         int root_x, int root_y)
+                         int root_x, int root_y, int *proto_out)
 {
   Window child_return, child, dummy, proxy;
-  int dest_x_return, dest_y_return;
-  int rc;
-  int actual_format;
-  unsigned long actual_size, bytes_remaining;
-  unsigned char *tmp_data;
-  XWindowAttributes attrs;
-  Atom actual_type;
-
+  int dest_x_return, dest_y_return, rc, proto;
   child_return = dpyinfo->root_window;
   dest_x_return = root_x;
   dest_y_return = root_y;
 
+  proto = -1;
+
   /* Not strictly necessary, but satisfies GCC.  */
   child = dpyinfo->root_window;
 
@@ -832,8 +830,33 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
           break;
         }
 
+      proxy = x_dnd_get_window_proxy (dpyinfo, child_return);
+
+      if (proxy != None)
+        {
+          proto = x_dnd_get_window_proto (dpyinfo, proxy);
+
+          if (proto != -1)
+            {
+              *proto_out = proto;
+
+              x_uncatch_errors_after_check ();
+              return proxy;
+            }
+        }
+
       if (child_return)
         {
+          proto = x_dnd_get_window_proto (dpyinfo, child_return);
+
+          if (proto != -1)
+            {
+              *proto_out = proto;
+              x_uncatch_errors_after_check ();
+
+              return child_return;
+            }
+
           rc = XTranslateCoordinates (dpyinfo->display,
                                       child, child_return,
                                       dest_x_return, dest_y_return,
@@ -850,36 +873,47 @@ x_dnd_get_target_window (struct x_display_info *dpyinfo,
       x_uncatch_errors_after_check ();
     }
 
-  if (child != None)
-    {
-      x_catch_errors (dpyinfo->display);
-      rc = XGetWindowProperty (dpyinfo->display, child,
-                               dpyinfo->Xatom_XdndProxy,
-                               0, 1, False, XA_WINDOW,
-                               &actual_type, &actual_format,
-                               &actual_size, &bytes_remaining,
-                               &tmp_data);
-
-      if (!x_had_errors_p (dpyinfo->display)
-          && rc == Success
-          && actual_type == XA_WINDOW
-          && actual_format == 32
-          && actual_size == 1)
-        {
-          proxy = *(Window *) tmp_data;
-          XFree (tmp_data);
+  *proto_out = x_dnd_get_window_proto (dpyinfo, child);
+  return child;
+}
+
+static Window
+x_dnd_get_window_proxy (struct x_display_info *dpyinfo, Window wdesc)
+{
+  int rc, actual_format;
+  unsigned long actual_size, bytes_remaining;
+  unsigned char *tmp_data;
+  XWindowAttributes attrs;
+  Atom actual_type;
+  Window proxy;
 
-          /* Verify the proxy window exists.  */
-          XGetWindowAttributes (dpyinfo->display, proxy, &attrs);
+  proxy = None;
+  x_catch_errors (dpyinfo->display);
+  rc = XGetWindowProperty (dpyinfo->display, wdesc,
+                           dpyinfo->Xatom_XdndProxy,
+                           0, 1, False, XA_WINDOW,
+                           &actual_type, &actual_format,
+                           &actual_size, &bytes_remaining,
+                           &tmp_data);
 
-          if (!x_had_errors_p (dpyinfo->display))
-            child = proxy;
-        }
+  if (!x_had_errors_p (dpyinfo->display)
+      && rc == Success
+      && actual_type == XA_WINDOW
+      && actual_format == 32
+      && actual_size == 1)
+    {
+      proxy = *(Window *) tmp_data;
+      XFree (tmp_data);
 
-      x_uncatch_errors_after_check ();
+      /* Verify the proxy window exists.  */
+      XGetWindowAttributes (dpyinfo->display, proxy, &attrs);
+
+      if (x_had_errors_p (dpyinfo->display))
+        proxy = None;
     }
+  x_uncatch_errors_after_check ();
 
-  return child;
+  return proxy;
 }
 
 static int
@@ -11616,10 +11650,12 @@ handle_one_xevent (struct x_display_info *dpyinfo,
             && dpyinfo == FRAME_DISPLAY_INFO (x_dnd_frame))
           {
             Window target;
+            int target_proto;
 
             target = x_dnd_get_target_window (dpyinfo,
                                               event->xmotion.x_root,
-                                              event->xmotion.y_root);
+                                              event->xmotion.y_root,
+                                              &target_proto);
 
             if (target != x_dnd_last_seen_window)
               {
@@ -11643,8 +11679,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 
                 x_dnd_wanted_action = None;
                 x_dnd_last_seen_window = target;
-                x_dnd_last_protocol_version
-                  = x_dnd_get_window_proto (dpyinfo, target);
+                x_dnd_last_protocol_version = target_proto;
 
                 if (target != None && x_dnd_last_protocol_version != -1)
                   x_dnd_send_enter (x_dnd_frame, target,
@@ -12849,10 +12884,12 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                   && dpyinfo == FRAME_DISPLAY_INFO (x_dnd_frame))
                 {
                   Window target;
+                  int target_proto;
 
                   target = x_dnd_get_target_window (dpyinfo,
                                                     xev->root_x,
-                                                    xev->root_y);
+                                                    xev->root_y,
+                                                    &target_proto);
 
                   if (target != x_dnd_last_seen_window)
                     {
@@ -12875,8 +12912,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                         }
 
                       x_dnd_last_seen_window = target;
-                      x_dnd_last_protocol_version
-                        = x_dnd_get_window_proto (dpyinfo, target);
+                      x_dnd_last_protocol_version = target_proto;
 
                       if (target != None && x_dnd_last_protocol_version != -1)
                         x_dnd_send_enter (x_dnd_frame, target,