Q75002: MDISubCl.exe Changes Background Color of MDI Client

Article: Q75002
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): _IK kbfile kbsample kbMDI kbOSWin2000 kbGrpDSUser kbOSWin310 kbWndw kbOSWin300
Last Modified: 09-JUL-2000

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SUMMARY
=======

MDISubCl.exe demonstrates how to alter the default background color of an MDI
client window by subclassing the MDI client window procedure and processing the
WM_ERASEBKGND message. All other messages are passed to the original MDI client
window procedure. Normally, a multiple-document interface (MDI) client window
defines its background color to be the system color value COLOR_BACKGROUND+1,
which is defined in the Windows SDK file WINDOWS.H. This value corresponds to
the window background color defined by the user in the Control Panel.

MORE INFORMATION
================

The following files are available for download from the Microsoft Download
Center:

  MDISubCl.exe

For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

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During processing of the WM_ERASEBKGND message, the class word that defines the
MDI client's background color is altered using the SetClassWord() function.
Then, control is passed to the original MDI client window procedure to paint and
update the window. When control returns from the original MDI client window
procedure, the MDI client's class word that defines the background color is set
back to its original value so that other MDI applications currently running are
not affected.

The following sample code from MDISubCl.exe is a sample window procedure that you
can use to subclass the default MDI client window procedure:

     LONG FAR PASCAL MdiClientWndProc(hwnd, msg, wParam, lParam)
     HWND hwnd;
     WORD msg, wParam;
     LONG lParam;
     {
       LONG lRetCode;

       switch (msg)
         {
       case WM_ERASEBKGND:
         {
         HBRUSH hbrNew, hbrOld;
                                            // create a solid purple brush
         hbrNew = CreateSolidBrush(RGB(75, 45, 145));
                                         // set the class background color
         hbrOld = SetClassWord(hwnd, GCW_HBRBACKGROUND, hbrNew);
                        // let the old window procedure handle the message
         lRetCode = CallWindowProc(lpfnMDIClientOld, hwnd, msg, wParam,
                     lParam);
                                  // set background back to original value
         SetClassWord(hwnd, GCW_HBRBACKGROUND, hbrOld);
         DeleteObject(hbrNew);         // all done with this, so delete it
         break;
         }

       default:
         lRetCode = CallWindowProc(lpfnMDIClientOld, hwnd, msg, wParam,
                     lParam);
         break;
         }
       return lRetCode;
     }

Additional query words:

======================================================================
Keywords          : _IK kbfile kbsample kbMDI kbOSWin2000 kbGrpDSUser kbOSWin310 kbWndw kbOSWin300 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1
Issue type        : kbinfo

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