I would like to send a button click (BM_CLICK) message to the Advanced button on the Port Settings tab of the Communications Port (COM1) Properties window (from the Device Manger). I know I can do this with sendkeys but I would like to use this as a learning experience with the FindWindow and SendMessage APIs.

I can get the window handle of the Communications Port (COM1) Properties window using the window caption in FindWindow:
windowTitle = serialPorts(index).name & " Properties" 'from WMI
parentHwnd = FindWindow(vbNullString, windowTitle)

I can even send messages to the OK and Cancel buttons using the class and button caption with FindWindowEX and SendMessage:
buttonHwnd = FindWindowEx(parentHwnd, 0&, "Button", "OK")
SendMessage buttonHwnd, BM_CLICK, 0&, 0&

I tried getting the window handle for the Port Settings tab and then the Advanced button but that doesn't work:
windowTitle = "Communications Port (" & serialPorts(index).deviceID & ") Properties"
parentHwnd = FindWindow(vbNullString, windowTitle)
childHwnd = FindWindowEx(parentHwnd, 0&, "#32770", "Port Settings")
buttonHwnd = FindWindowEx(childHwnd, 0&, "Button", "&Advanced...")

How do I do this?

Thanks,
quantum1976