protected virtual void OnFullscreenChanged() {
FullscreenChanged?.Invoke(this, EventArgs.Empty);
if (_fullscreenEnabled) {
Form.FormBorderStyle = FormBorderStyle.None;
Form.WindowState = FormWindowState.Maximized;
} else {
Form.FormBorderStyle = FormBorderStyle.Sizable;
Form.WindowState = FormWindowState.Normal;
}
}