Mdi窗体客户区无边框显示

#region 系统API
// Win32 Constants
private const int GWL_STYLE = -16;
private const int GWL_EXSTYLE = -20;

private const int WS_BORDER = 0x00800000;
private const int WS_EX_CLIENTEDGE = 0x00000200;

private const uint SWP_NOSIZE = 0x0001;
private const uint SWP_NOMOVE = 0x0002;
private const uint SWP_NOZORDER = 0x0004;
private const uint SWP_NOREDRAW = 0x0008;
private const uint SWP_NOACTIVATE = 0x0010;
private const uint SWP_FRAMECHANGED = 0x0020;
private const uint SWP_SHOWWINDOW = 0x0040;
private const uint SWP_HIDEWINDOW = 0x0080;
private const uint SWP_NOCOPYBITS = 0x0100;
private const uint SWP_NOOWNERZORDER = 0x0200;
private const uint SWP_NOSENDCHANGING = 0x0400;

// Win32 方法
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern int GetWindowLong(IntPtr hWnd, int Index);

[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern int SetWindowLong(IntPtr hWnd, int Index, int Value);

[DllImport("user32.dll", ExactSpelling = true)]
private static extern int SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter,
int X, int Y, int cx, int cy, uint uFlags);

private void MainForm_Shown(object sender, EventArgs e)
{
//获取mdi客户区
MdiClient mdiClient = null;
for (int i = 0; i < this.Controls.Count; i++)
{

mdiClient = this.Controls[i] as MdiClient;
if (mdiClient != null)
{
// 找到了mdi客户区
// 取得客户区的边框
int style = GetWindowLong(mdiClient.Handle, GWL_STYLE);
int exStyle = GetWindowLong(mdiClient.Handle, GWL_EXSTYLE);
style &= ~WS_BORDER;
exStyle &= ~WS_EX_CLIENTEDGE;

// 调用win32设定样式
SetWindowLong(mdiClient.Handle, GWL_STYLE, style);
SetWindowLong(mdiClient.Handle, GWL_EXSTYLE, exStyle);

// 更新客户区
SetWindowPos(mdiClient.Handle, IntPtr.Zero, 0, 0, 0, 0,
SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER |
SWP_NOOWNERZORDER | SWP_FRAMECHANGED);
UpdateStyles();
break;
}
}
}
#endregion