I create a window ...
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invoke CreateWindowEx,0,class,0,WS_VISIBLE,128,128,300,200,NULL,NULL,[wc.hInstance],NULL
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;-----------------------

I create a dialogbox ...
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invoke DialogBoxParam,[hInstance],1000,HWND_DESKTOP,DialogProc,0
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"
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resource dialogs,\
1000,LANG_ENGLISH+SUBLANG_DEFAULT,MainDialog

dialog MainDialog,'Nothing',128,128,300,200,DS_MODALFRAME
enddialog

;-----------------------

everything is ok,
but...

The position and the size on the screen are definitely not the same !!

Seems that only the createwindow coordinates correspond to my grafikcard (1280x800).

Where is the secret ?

The dialog coordinates AND sizes of all controls on the dialog are in so called "dialog units" -- not pixels as in case of CreateWindowEx.
This will help:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms645475(v=vs.85).aspx

AsmGuru,
thank you. I knew, it was something easy and logic like that