P/Invoke for hiding the Close button of a WPF Window

gistfile1.cs

internal static class Win32
{
	private const int GWL_STYLE = -16;
	private const int WS_SYSMENU = 0x80000;

	[DllImport("user32.dll", SetLastError = true)]
	private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

	[DllImport("user32.dll")]
	private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

	public static void HideCloseButton(this Window window)
	{
		var hwnd = new WindowInteropHelper(window).Handle;
		SetWindowLong(hwnd, GWL_STYLE, GetWindowLong(hwnd, GWL_STYLE) & ~WS_SYSMENU);
	}
}