# HG changeset patch
# User aidan
# Date 1109788317 0
# Node ID 140bb0f4da004306bc862ec4b5a188f25edacd9e
# Parent  63a49b9b070cf436959ca5cfa88f16b8d68d9f7e
[xemacs-hg @ 2005-03-02 18:31:55 by aidan]
Wrap call to XtRegisterDrawable with check that XtWindowToWidget gives NULL,
document why.

diff -r 63a49b9b070c -r 140bb0f4da00 src/ChangeLog
--- a/src/ChangeLog	Wed Mar 02 17:55:25 2005 +0000
+++ b/src/ChangeLog	Wed Mar 02 18:31:57 2005 +0000
@@ -1,3 +1,9 @@
+2005-03-02  Aidan Kehoe  <kehoea@parhasard.net>
+
+	* select-x.c (x_reply_selection_request): Check that
+	XtWindowToWidget returns NULL before calling XtRegisterDrawable,
+	document why. 
+
 2005-03-02  Aidan Kehoe  <kehoea@parhasard.net>
 
 	* select-x.c (x_reply_selection_request): Make the error message
diff -r 63a49b9b070c -r 140bb0f4da00 src/select-x.c
--- a/src/select-x.c	Wed Mar 02 17:55:25 2005 +0000
+++ b/src/select-x.c	Wed Mar 02 18:31:57 2005 +0000
@@ -545,8 +545,24 @@
          target window, rather, pass them to us. This would be a hack, but
          the Xt selection routines are broken for our purposes--we can't
          pass them callbacks from Lisp, for example. Let's call it a
-         workaround. */
-      XtRegisterDrawable(display, (Drawable)window, widget);
+         workaround.
+
+	 The call to wait_for_property_change means we can break out of that
+	 function, switch to another frame on the same display (which will
+	 be another Xt widget), select a huge amount of text, and have the
+	 same (foreign) app ask for another incremental selection
+	 transfer. Programming like X11 made sense, would mean that, in that
+	 case, XtRegisterDrawable is called twice with different widgets.
+
+	 Since the results of calling XtRegisterDrawable when the drawable
+	 is already registered with another widget are undefined, we want to
+	 avoid that--so, only call it when XtWindowToWidget returns NULL,
+	 which it will only do with a valid Window if it's not already
+	 registered. */
+      if (NULL == XtWindowToWidget(display, window))
+      {
+	XtRegisterDrawable(display, (Drawable)window, widget);
+      }
 
       prop_id = expect_property_change (display, window, reply.property,
 					PropertyDelete);