findwindowex and class name

[cricrides]

Hello

I am a bit stucked and need help.
I have an application that needs to find the window handle of an MDI form of another app.
So globally, I use:
wHandle = FindWindow(Nothing, "AppName")
wHandle2 = FindWindowEx(wHandle, 0&, "WindowsForms10.MDICLIENT.app.0." + appDomainHexedHash, "")
wHandle3 = FindWindowEx(wHandle2, wHandle3, "WindowsForms10.Window.8.app.0." + appDomainHexedHash, "Form1")

As an Hash code is added to the class name at runtime (see Spy++), I need to find this hashcode of the external app to get the correct class name.

How can I do that?
Is there a 'more intelligent' way of finding the whandle?

Thanks a lot for your help

cricri