PRB: FatalExit 0x0001 Possible If WM_CTLCOLOR Used Improperly

ID: Q42458

The information in this article applies to:

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

SUMMARY

An application can change the colors of a dialog box by creating a brush of the desired color and processing the WM_CTLCOLOR message to return a handle to the brush. If the brush is not a stock object, the application should create the brush before the dialog box is displayed and store its handle in a global or static variable. Do not use the following code in a dialog box procedure:


   case WM_CTLCOLOR:  // Create green edit fields
      if (HIWORD(lParam) == CTLCOLOR_EDIT)
         return CreateSolidBrush(RGB(0, 255, 0));
      break;

Windows sends a WM_CTLCOLOR message to the dialog box procedure each time any changes are made to the dialog box (such as when the user presses a button or moves the focus to a new control). In the code above, each time the application processes a WM_CTLCOLOR message for an edit control, the application creates a new brush which is stored in the GDI data segment. If the GDI data segment fills completely, Windows generates a FatalExit 0x0001 (insufficient memory for allocation) error for each subsequent allocation.

MORE INFORMATION

To avoid this error, modify the application to call the CreateSolidBrush function once, either outside the application's message loop or during the processing of the WM_CREATE message. Store the returned brush handle in a global or static variable. An advantage of this method is that the brush can be used in any part of the application without consuming any additional system resources.

The following code provides a skeleton for the WinMain procedure and for the dialog procedure to implement this method:


   // WinMain
   HBRUSH  hBrushGreen; // Global variable

   WinMain (...)
   {
      // Register window class and create window

      hBrushGreen = CreateSolidBrush(RGB(0, 255, 0));

      while (GetMessage(...))
        {
        TranslateMessage(...);
        DispatchMessage(...);
        }

      DeleteObject(hBrushGreen);
      return msg.wparam;
   }

   // Dialog box procedure
      case WM_CTLCOLOR: // Green edit fields
         if (HIWORD(lParam) == CTLCOLOR_EDIT)
            return hBrushGreen;
         break;

Additional query words:

Keywords : kb16bitonly kbDlg kbSDKPlatform kbGrpUser
Version : WINDOWS:3.0,3.1
Platform : WINDOWS
Issue type : kbprb