VS 2010 Simulate a mouse click Without activate the window

With the API SendMessage

NativeMethods.SendMessage(Hwnd, WM_LBUTTONDOWN, 1, lParam)
NativeMethods.SendMessage(Hwnd, WM_LBUTTONUP, 0, lParam)

I can simulate a mouse click even if the window is NOT in the foreground, also if it's not visible and also if the point to press is out of the screen. Very well, it's what I want.

But after execute the code the window also jumps in the foreground... :(

Question: how to simulate the mouse click (into a window that is not visible) without activate the window and without it jumps in the foreground?

ty :)