Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!swrinde!cs.utexas.edu!rice!uw-beaver!uw-june!fred.cs.washington.edu!slh
From: slh@fred.cs.washington.edu (Scott Heyano)
Newsgroups: comp.os.os2
Subject: Re: OS/2 PM Programming
Summary: WinSetWindowULong(...,QWL_STYLE,...&~FS_SIZEBORDER)
Keywords: OS/2, SIZEBORDER
Message-ID: <9809@june.cs.washington.edu>
Date: 14 Nov 89 21:02:03 GMT
References: <12642@mergvax>
Sender: news@cs.washington.edu
Reply-To: slh@fred.cs.washington.edu (Scott Heyano)
Organization: University of Washington, Computer Science, Seattle
Lines: 6

I think this will work:
	oldStyle = WinQueryWindowULong (hwndFrame, QWL_STYLE);
	WinSetWindowULong (hwndFrame, QWL_STYLE, oldStyle&~FS_SIZEBORDER);
where hwndFrame is the frame window of the your client.
This or something close to it should work.
Or maybe not.