You use the TV_INSERTSTRUCT declare. This is correct: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct TVITEM { public int mask; public IntPtr hItem; public int state; public int stateMask; public IntPtr pszText; public int cchTextMax; public int iImage; public int iSelectedImage; public int cChildren; public IntPtr lParam; }

I have used this InterOp snippet: private const uint MOUSEEVENTF_LEFTDOWN = 0x0002; private const uint MOUSEEVENTF_LEFTUP = 0x0004; [DllImport("user32.dll")] private static extern void mouse_event( uint dwFlags, // motion and click options uint dx, // horizontal position or change uint dy, // vertical position or change uint dwData, // wheel movement IntPtr dwExtraInfo // application-defined information ); private static void SendClick(Point location) { Cursor.Position = location; mouse_event(MOUSEEVENTF_LEFTDOWN, 0, 0, 0, IntPtr.Zero); mouse_event(MOUSEEVENTF_LEFTUP, 0, 0, 0, IntPtr.Zero); }