[DllImport("user32.dll")] static extern bool PostMessage(IntPtr hWnd, uint Msg, int wParam, int lParam); const int WM_LBUTTONDOWN = 0x0201; const int WM_LBUTTONUP = 0x0202; PostMessage(hWnd, WM_LBUTTONDOWN, 1, 0); PostMessage(hWnd, WM_LBUTTONUP, 0, 0);