C# 窗口置顶

[DllImport("User32.dll", EntryPoint = "SetWindowLong", SetLastError = true)]
public static extern bool SetWindowLong(IntPtr hWnd, int nIndex, int nFlags);
[DllImport("User32.dll", EntryPoint = "SetLayeredWindowAttributes", SetLastError = true)]
public static extern int GetWindowLong(IntPtr hWnd, int nFlags);
[DllImport("User32.dll", EntryPoint = "SetWindowPos", SetLastError = true)]
public static extern int SetWindowPos(IntPtr hWnd, IntPtr hWndWinInsertAfter, int x, int y, int cx, int cy, int nFlags);

const int WS_EX_TOOLWINDOW = 0x80;
const int GWL_EXSTYLE = -20;
const int HWND_TOPMOST = -1;
const int SWP_NOSIZE = 0x0001;
const int SWP_NOMOVE = 0x0002;

private void Window_Loaded(object sender, RoutedEventArgs e)
{
HwndSource hs = (HwndSource)PresentationSource.FromDependencyObject(this);
IntPtr ip = hs.Handle;
SetWindowLong(ip, GWL_EXSTYLE, GetWindowLong(ip, GWL_EXSTYLE) | WS_EX_TOOLWINDOW);
SetWindowPos(ip, (IntPtr)HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);
}