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Sublassing a window question

Posted on 1998-12-30
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Last Modified: 2013-11-20
Hello EveryBody !
When I try to subclass a normal window ( Dialog that is existent on my desktop ) I fail at the stage of check whether the HWND is already attached to a permanent CWND* .
Is there any way to make such a subclass ?
I want to get messages that go to the specific window that was opened by another application . I dont want to use System Hooks method .
Any ideas ?

Thank you in advance ,
Oleg
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Question by:Maizlish
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Expert Comment

by:koskia
ID: 1326993
As far as I know you're trying something that you can't do
subclassing a window is only within your application
if it wasn't so, you could get into other applications (Photoshop, Netscape, IE, etc. ...)
anything really, and control them through your app.
the given answer is that a window can only be subclassed once.
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Accepted Solution

by:
Tommy Hui earned 100 total points
ID: 1326994
Sorry, but under Win32 you will need to break the process boundaries between applications somehow. One way is to use a system hook. Since you indicated you didn't want to use this method, there are others.

1. Inject a DLL into all applications by using the registry
  HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_DLLs
Note that this only works for NT systems.

2. Use CreateRemoteThread(). This again is only on NT systems as Win9x does not support this method.

3. If you are interested in a particular process, you can use the debugging APIs and force it to do a LoadLibrary() of your DLL at the start. This is completely portable, but only affects programs you start explicitly.

4. Use SetWindowsHookEx(). This is portable and affects all applications.

PS. It is possible to subclass a window multiple times. What you are running into is that MFC does not allow you subclass windows you did not create, which is why it is necessary to break through process boundaries.
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