colordialogbutton: Actually accept NULL

As pointed out in #5321, my previous fix was not
good enough.

Fixes: #5321

diff --git a/gtk/gtkcolordialogbutton.c b/gtk/gtkcolordialogbutton.c
index 139d9f7eb1a27212dabb0f715851160651b52ff1..b854ee56214c62a41b21114982f91687b7b8b1e5 100644 (file)
--- a/gtk/gtkcolordialogbutton.c
+++ b/gtk/gtkcolordialogbutton.c
@@ -449,7 +449,7 @@ gtk_color_dialog_button_set_dialog (GtkColorDialogButton *self,
                                     GtkColorDialog       *dialog)
 {
   g_return_if_fail (GTK_IS_COLOR_DIALOG_BUTTON (self));
-  g_return_if_fail (GTK_IS_COLOR_DIALOG (dialog));
+  g_return_if_fail (dialog == NULL || GTK_IS_COLOR_DIALOG (dialog));
 
   if (!g_set_object (&self->dialog, dialog))
     return;