Summary

Support client-side window decorations in JavaFX, allowing applications to place JavaFX controls in the header bar.

Problem

Modern applications often use client-side window decorations, where the client area is extended to cover the entire window. This allows applications to place controls in the header bar area, and style it to create a cohesive look and feel with the rest of the application.

Solution

The new EXTENDED stage style is added, which enables the platform toolkit integration necessary to support client-side window decorations. In addition, the javafx.scene.layout.HeaderBar control is added, which applications need to use to replace the system-provided header bar. The HeaderBar control provides the "click and drag" and "double-click to maximize" behaviors for the window, as well as platform-specific window manager integrations like snap layouts on Windows.

By default, the HeaderBar control comes with default header buttons that mimic the platform-native header buttons (iconify, maximize, close). If more control is desired, the default header buttons can be removed, allowing applications to use standard JavaFX buttons instead.