[gtkmm/gtkmm-3-24] Gtk::AboutDialog: Add constructor with a use_header_bar parameter

[Kjell Ahlstedt <kjellahl src gnome org>]

commit c3404efb044859a209b80c10510974ddbe0eaf71
Author: Murray Cumming <murrayc murrayc com>
Date:   Sun Nov 4 17:14:19 2018 +0100

    Gtk::AboutDialog: Add constructor with a use_header_bar parameter
    
    Bug #780004 (Daniel Boles)

 gtk/src/aboutdialog.ccg | 8 ++++++++
 gtk/src/aboutdialog.hg  | 9 +++++++++
 2 files changed, 17 insertions(+)
---
diff --git a/gtk/src/aboutdialog.ccg b/gtk/src/aboutdialog.ccg
index 6a17370a..6382f3ca 100644
--- a/gtk/src/aboutdialog.ccg
+++ b/gtk/src/aboutdialog.ccg
@@ -23,6 +23,14 @@
 namespace Gtk
 {
 
+// use-header-bar is construct-only. It must be set in the constructor,
+// if you don't want the default value.
+AboutDialog::AboutDialog(bool use_header_bar)
+:
+  _CONSTRUCT("use-header-bar", static_cast<int>(use_header_bar))
+{
+}
+
 void AboutDialog::unset_license()
 {
   gtk_about_dialog_set_license(gobj(), nullptr);
diff --git a/gtk/src/aboutdialog.hg b/gtk/src/aboutdialog.hg
index 32dfcdd7..323184c5 100644
--- a/gtk/src/aboutdialog.hg
+++ b/gtk/src/aboutdialog.hg
@@ -53,6 +53,15 @@ class AboutDialog : public Dialog
 public:
   _CTOR_DEFAULT()
 
+  /** Constructor.
+   *
+   * @param use_header_bar <tt>true</tt> if the dialog shall use a HeaderBar
+   *        for action buttons instead of the action-area.
+   *
+   * @newin{3,24}
+   */
+  explicit AboutDialog(bool use_header_bar);
+
   _WRAP_METHOD(Glib::ustring get_program_name() const, gtk_about_dialog_get_program_name)
   _WRAP_METHOD(void set_program_name(const Glib::ustring& name), gtk_about_dialog_set_program_name)