FIX: Visual Workbench Cannot Find WndProc in Windows 3.1 Apps

WINDOWS   | WINDOWS NT

The information in this article applies to:

• The Visual Workbench Integrated Debugger, included with:

      - Microsoft Visual C++ for Windows, versions 1.0 and 1.5
      - Microsoft Visual C++, 32-bit Edition, version 1.0
  

SYMPTOMS

The Visual Workbench debugger allows you to set a breakpoint in a window procedure. This makes it possible for the application being debugged to break in the function when a specific message or class of messages is received. If the Windows version 3.1 prototype is used for the window procedure, the Visual Workbench is not able to identify the function as a window procedure. As a result, the WndProc list box in the Breakpoints dialog box that lists the available window procedures does not list the function.

CAUSE

The Visual Workbench uses the Windows version 3.0 WndProc prototype, which reads as follows:

         long _far _pascal WndProc(WORD, WORD, WORD, LONG)

         long _far _pascal WndProc(HWND, UINT, WPARAM, LPARAM)

RESOLUTION

Even though it is not possible to select the window procedure to break in from the WndProc list box in the Breakpoints dialog box, it is possible to manually enter the name of the function.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was corrected in Visual C++ version 2.0.

MORE INFORMATION

To reproduce the problem, do the following:

1. Build a debug version of any of the Windows samples provided with Visual C++.

2. When the build is completed, choose Breakpoints from the Debug menu.

3. In the Type field, choose "Break at WndProc if Message is Received". The second item in the dialog box will change to "WndProc"; however, the list box will not contain any Windows procedures.