PRB: Class Browser Causes System Error on Exit

• Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a on the following platform: Win95

SYMPTOMS

If either of the TreeView ActiveX controls in the Class Browser have focus when you press Escape to close the Class Browser, a General Protection Fault (GPF) or Invalid Page Fault occurs. This problem occurs only under Windows 95; it does not occur under Windows NT.

CAUSE

This occurs when a new version of Comctl32.ocx has been installed. This problem occurs with any version of this file dated 1/16/97 or later.

The problem actually occurs in any form using the ActiveX controls from this .ocx file if the form is released before the code associated with the ActiveX control is completed.

RESOLUTION

Follow these steps to implement an add-in for the Class Browser to fix the problem described above:

1. Create a program named Brwescfx.prg in the root Visual FoxPro directory with the following code:

         *  Program...........: Brwescfx.prg
         *  Author............: Ken R. Levy
         *  Copyright.........: None (Public Domain)
         *  Description.......: VFP 5.0 Class Browser patch for 1-16-97
         *                      COMCTL32.OCX bug.
         *  Note:  This add-in patch only fixes GPFs that occur when pressing
         *  ESC to exit.
         *
         *  Instructions for installation:
         *  1. Save Brwescfx.prg program file above into your VFP home/root
         *     directory.
         *  2. Launch the Class Browser in VFP 5.0 and open any VCX.
         *  3. Run Barwescfx.prg to automatically register the BrwESCFx Class
         *     Browser add-in.
         *  4. No more GPFs will occur using the Class Browser when pressing
         *     ESC.
         *
   
         LPARAMETERS oSource
   
         IF TYPE("oSource")#"O" OR ISNULL(oSource)
             IF TYPE("_oBrowser")#"O" OR ISNULL(_oBrowser)
                 MESSAGEBOX("You must have the Class Browser running " + ;
                     "to register BrwESCFx.", 48,"BrwESCFx")
                 RETURN .F.
             ENDIF
             IF _oBrowser.AddIn("BrwESCFx",HOME()+"BrwESCFx","QueryUnload")
                 MESSAGEBOX("BrwESCFx has successfully been " + ;
                     "registered.",0,"BrwESCFx")
                 RETURN
             ENDIF
             MESSAGEBOX("BrwESCFx failed to be registered.",16,"BrwESCFx")
             RETURN .F.
         ENDIF
         IF NOT oSource.cAddInMethod=="QUERYUNLOAD"
             RETURN .F.
         ENDIF
         IF TYPE("_screen.ActiveForm.ActiveControl")#"O" OR ;
             LOWER(LEFT(_screen.ActiveForm.ActiveControl.Name,3))=="ole"
             oSource.lNoDefault=.T.
             oSource.cboClassType.SetFocus
             KEYBOARD "{ESC}" PLAIN
         ENDIF
         RETURN
         *  END PROGRAM: BrwESCFx.PRG
   
   

2. Launch the Class Browser in Visual FoxPro and open any VCX.

3. Run Brwescfx.prg (created in Step 1) to automatically register the BrwESCFx Class Browser add-in.

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Behavior

1. Launch the Class Browser and open any VCX.

2. Click in one of the TreeView controls to ensure it has focus.

3. Press Escape to exit the Class Browser.