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From: bobg@mirror.UUCP (Bob Goodearl)
Newsgroups: comp.windows.ms
Subject: Re: RegisterClass in DLL
Message-ID: <34458@mirror.UUCP>
Date: 29 Dec 89 16:52:57 GMT
References: <6970014@hpmcaa.mcm.hp.com>
Reply-To: bobg@mirror.TMC.COM (Bob Goodearl)
Organization: Mirror Systems, Cambridge Mass.
Lines: 22

In article <6970014@hpmcaa.mcm.hp.com> marco@hpmcaa.mcm.hp.com
 (Marco Dalla-Gasperina) writes:
=>I'm having a problem registering a window class inside a DLL...  It seems
=>to work for a "few" times (usually 3) but then it fails?
=>

When writing DLL code, I found that a window class registered using the
DLL instance handle caused problems.  If the application calling the
DLL was closed and then started a second time without exiting windows
first, the call to RegisterClass in the DLL would fail the second time.
The solution I found was to use the parent application's instance
handle when calling RegisterClass in the DLL.  This works for the code
I'm writing because only 1 application can use the DLL and only 1
instance of the application can exist at any one time.

Along the way, I tried bypassing RegisterClass if the DLL had been
initialized previously, but then the call to CreateWindow failed when
using that class.

Hope this is of some use to you.
===
Bob