>I want know how can I do to check if another application it's open,
>for example: MSPaint.EXE
>
>I'm working with a form that contains a image control and when I click
>in that MSPaint is open, if user click again, I don't want open MSPaint again.

There's a function that I've written (Is_Run/Is_Run32) that will allow you to determine if an application is already running. It's available in the Files section under Win32 and other APIs. The problem with GETOBJECT() is that it won't work unless the application is an OLE server.