[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
 
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr GetWindow(IntPtr hWnd, uint uCmd);
 
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

int x = 100; // X coordinate of the click
int y = 100; // Y coordinate of the click
IntPtr handle = WbTmall.Handle;
StringBuilder className = new StringBuilder(100);
while (className.ToString() != "Internet Explorer_Server") // The class control for the browser
{
 handle = GetWindow(handle, 5); // Get a handle to the child window
 GetClassName(handle, className, className.Capacity);
}
 
IntPtr lParam = (IntPtr)((y << 16) | x); // The coordinates
IntPtr wParam = IntPtr.Zero; // Additional parameters for the click (e.g. Ctrl)
const uint downCode = 0x201; // Left click down code
const uint upCode = 0x202; // Left click up code
SendMessage(handle, downCode, wParam, lParam); // Mouse button down
SendMessage(handle, upCode, wParam, lParam); // Mouse button up