How can I make a child process window to appear modal in my process?

Question

I have an application that calls some other utility application to set some settings for a particular device. That utility application is called using ShellExecuteEx.

So

Answer 1

EnableWindow is correct, this is generally how message boxes and other "modal" windows do it. As for zorder changing, you can intercept the WM_WINDOWPOSCHANGING message and set the SWP_NOZORDER flag to prevent the zorder change. Make sure you only do this while you are setting EnableWindow(false).