HeaderBarProtocol

public protocol HeaderBarProtocol : WidgetProtocol

GtkHeaderBar is a widget for creating custom title bars for windows.

GtkHeaderBar is similar to a horizontal GtkCenterBox. It allows children to be placed at the start or the end. In addition, it allows the window title to be displayed. The title will be centered with respect to the width of the box, even if the children at either side take up different amounts of space.

GtkHeaderBar can add typical window frame controls, such as minimize, maximize and close buttons, or the window icon.

For these reasons, GtkHeaderBar is the natural choice for use as the custom titlebar widget of a GtkWindow (see [methodGtk.Window.set_titlebar`]), as it gives features typical of titlebars while allowing the addition of child widgets.

GtkHeaderBar as GtkBuildable

The GtkHeaderBar implementation of the GtkBuildable interface supports adding children at the start or end sides by specifying “start” or “end” as the “type” attribute of a <child> element, or setting the title widget by specifying “title” value.

By default the GtkHeaderBar uses a GtkLabel displaying the title of the window it is contained in as the title widget, equivalent to the following UI definition:

<object class="GtkHeaderBar">
  <property name="title-widget">
    <object class="GtkLabel">
      <property name="label" translatable="yes">Label</property>
      <property name="single-line-mode">True</property>
      <property name="ellipsize">end</property>
      <property name="width-chars">5</property>
      <style>
        <class name="title"/>
      </style>
    </object>
  </property>
</object>

CSS nodes

headerbar
╰── windowhandle
    ╰── box
        ├── box.start
        │   ├── windowcontrols.start
        │   ╰── [other children]
        ├── [Title Widget]
        ╰── box.end
            ├── [other children]
            ╰── windowcontrols.end

A GtkHeaderBar‘s CSS node is called headerbar. It contains a windowhandle subnode, which contains a box subnode, which contains two box subnodes at the start and end of the header bar, as well as a center node that represents the title.

Each of the boxes contains a windowcontrols subnode, see [classGtk.WindowControls] for details, as well as other children.

Accessibility

GtkHeaderBar uses the GTK_ACCESSIBLE_ROLE_GROUP role.

The HeaderBarProtocol protocol exposes the methods and properties of an underlying GtkHeaderBar instance. The default implementation of these can be found in the protocol extension below. For a concrete class that implements these methods and properties, see HeaderBar. Alternatively, use HeaderBarRef as a lighweight, unowned reference if you already have an instance you just want to use.