Navigator: windowControlsOverlay property

The windowControlsOverlay property of the Navigator interface returns the WindowControlsOverlay interface, which exposes information about the title bar geometry in desktop Progressive Web Apps that use the Window Controls Overlay API.

Progressive Web Apps installed on desktop Operating Systems can opt-in to the Window Controls Overlay feature by using the window-controls-overlay value in the display_override web app manifest member.

Doing so hides the default window title bar and gives the app access to the full area of the app window.

if ("windowControlsOverlay" in navigator) {
  const rect = navigator.windowControlsOverlay.getTitlebarAreaRect();
  // Do something with the title bar area rectangle.
} else {
  // The Window Controls Overlay feature is not available.
}