public class HeaderBar : Widget, Accessible, Buildable, ConstraintTarget
`GtkHeaderBar` is a widget for creating custom title bars for windows.
![An example GtkHeaderBar](headerbar.png)
`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 [ method@Gtk.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:
```xml <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> ```
``` 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 [class@Gtk.WindowControls] for details, as well as other children.
`GtkHeaderBar` uses the gtk_accessible_role_group role.