From 334b362bf46859bc581643b0fab6674b4c5e1b54 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Fri, 4 Feb 2022 10:11:31 +0800
Subject: [PATCH] Make `x-gtk-use-native-input' take effect immediately

* lisp/term/x-win.el (x-internal-focus-input-context): New
declaration.
(x-gtk-use-native-input-watcher): New variable watcher.
* src/xfns.c (Fx_internal_focus_input_context): New function.
(syms_of_xfns): Define new subr.
---
 lisp/term/x-win.el | 14 ++++++++++++++
 src/xfns.c         | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/lisp/term/x-win.el b/lisp/term/x-win.el
index 019a01e22ca..80a7d81d084 100644
--- a/lisp/term/x-win.el
+++ b/lisp/term/x-win.el
@@ -1563,6 +1563,20 @@ EVENT is a preedit-text event."
 
 (defvaralias 'x-gtk-use-system-tooltips 'use-system-tooltips)
 
+(declare-function x-internal-focus-input-context (frame) "xfns.c")
+
+(defun x-gtk-use-native-input-watcher (_symbol newval &rest _ignored)
+  "Variable watcher for `x-gtk-use-native-input'.
+If NEWVAL is non-nil and the selected frame is displayed through X,
+focus the GTK input context."
+  (when (and (featurep 'gtk)
+             newval
+             (eq (framep (selected-frame)) 'x))
+    (x-internal-focus-input-context (selected-frame))))
+
+(add-variable-watcher 'x-gtk-use-native-input
+                      #'x-gtk-use-native-input-watcher)
+
 (provide 'x-win)
 (provide 'term/x-win)
 
diff --git a/src/xfns.c b/src/xfns.c
index 7007f70b191..7ca791afa18 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -8565,6 +8565,22 @@ DEFUN ("x-gtk-debug", Fx_gtk_debug, Sx_gtk_debug, 1, 1, 0,
 #endif /* GTK_CHECK_VERSION (3, 14, 0) */
 #endif /* HAVE_GTK3 */
 #endif	/* USE_GTK */
+
+DEFUN ("x-internal-focus-input-context", Fx_internal_focus_input_context,
+       Sx_internal_focus_input_context, 1, 1, 0,
+       doc: /* Focus and set the client window of FRAME's GTK input context.
+This should be called from a variable watcher for `x-gtk-use-native-input'.  */)
+  (Lisp_Object frame)
+{
+#ifdef USE_GTK
+  struct frame *f = decode_window_system_frame (frame);
+  GtkWidget *widget = FRAME_GTK_OUTER_WIDGET (f);
+
+  gtk_im_context_focus_in (FRAME_X_OUTPUT (f)->im_context);
+  gtk_im_context_set_client_window (FRAME_X_OUTPUT (f)->im_context,
+				    gtk_widget_get_window (widget));
+#endif
+}
 
 /***********************************************************************
 			    Initialization
@@ -8942,6 +8958,8 @@ eliminated in future versions of Emacs.  */);
   defsubr (&Sx_select_font);
 #endif
 
+  defsubr (&Sx_internal_focus_input_context);
+
 #ifdef USE_CAIRO
   defsubr (&Sx_export_frames);
 #ifdef USE_GTK
-- 
2.39.5