C# 实现无焦点窗体（转载）

#region 无焦点窗体

[System.Runtime.InteropServices.DllImport("user32.dll")]
 private extern static IntPtr SetActiveWindow(IntPtr handle);
 private const int WM_ACTIVATE = 0x006;
 private const int WM_ACTIVATEAPP = 0x01C;
 private const int WM_NCACTIVATE = 0x086;
 private const int WA_INACTIVE = 0;
 private const int WM_MOUSEACTIVATE = 0x21;
 private const int MA_NOACTIVATE = 3;
 protected override void WndProc(ref Message m)
 {
 if (m.Msg == WM_MOUSEACTIVATE)
 {
 m.Result = new IntPtr(MA_NOACTIVATE);
 return;
 }
 else if (m.Msg == WM_NCACTIVATE)
 {
 if (((int)m.WParam & 0xFFFF) != WA_INACTIVE)
 {
 if (m.LParam != IntPtr.Zero)
 {
 SetActiveWindow(m.LParam);
 }
 else
 {
 SetActiveWindow(IntPtr.Zero);
 }
 }
 }
 base.WndProc(ref m);
 }

#endregion