headerbar: remove G_PARAM_CONSTRUCT from custom-title

This fixes the ability to sublcass GtkHeaderBar from a UI template which
contains a custom <child type="title"> element.

https://bugzilla.gnome.org/show_bug.cgi?id=757544

diff --git a/gtk/gtkheaderbar.c b/gtk/gtkheaderbar.c
index 53bd4d5c4c74dfb16dfd1fa4bb2c78a363898a7e..a1f060622da6461ffa7ae81bad876836be1485ee 100644 (file)
--- a/gtk/gtkheaderbar.c
+++ b/gtk/gtkheaderbar.c
@@ -1892,7 +1892,7 @@ gtk_header_bar_class_init (GtkHeaderBarClass *class)
                            P_("Custom Title"),
                            P_("Custom title widget to display"),
                            GTK_TYPE_WIDGET,
-                           G_PARAM_READWRITE|G_PARAM_CONSTRUCT|G_PARAM_STATIC_STRINGS);
+                           G_PARAM_READWRITE|G_PARAM_STATIC_STRINGS);
 
   header_bar_props[PROP_SPACING] =
       g_param_spec_int ("spacing",