[gtk/gtk-3-22] wayland: Don't emit signals if nothing changed

[Daniel Boles <dboles src gnome org>]

commit 4b95d7406821196615149fb2527840ff14626a03
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Mar 26 21:38:28 2018 -0400

    wayland: Don't emit signals if nothing changed
    
    We were emitting a preedit-changed even if the preedit text did
    not actually change, causing text views to scroll.
    
    https://gitlab.gnome.org/GNOME/gtk/issues/132
    https://gitlab.gnome.org/GNOME/gtk/merge_requests/83#note_93411

 modules/input/imwayland.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/modules/input/imwayland.c b/modules/input/imwayland.c
index 89b2f7af1a..bc710450d5 100644
--- a/modules/input/imwayland.c
+++ b/modules/input/imwayland.c
@@ -101,6 +101,9 @@ static const GtkIMContextInfo *info_list[] =
 static void
 reset_preedit (GtkIMContextWayland *context)
 {
+  if (context->preedit.text == NULL)
+    return;
+
   g_clear_pointer (&context->preedit.text, g_free);
   context->preedit.cursor_idx = 0;
   g_signal_emit_by_name (context, "preedit-changed");