PRB: MFC ActiveX Control Ignores ARROW Keys on VB Container

• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0
• Microsoft Visual C++, 32-bit Editions, version 5.0
• Microsoft Visual Studio 97

SYMPTOMS

An MFC ActiveX Control that contains a subclassed Edit control does not respond to the ARROW keys. More specifically, when a Visual Basic form contains the MFC ActiveX Control and the control has focus, the ARROW keys are not recognized.

CAUSE

This behavior is the result of ARROW keys being accelerator keys. Accelerator keys are handled in the main message loop of the containing application before the window procedure of the control is called. As a result, the MFC ActiveX control is not aware that the ARROW keys have been pressed. Other accelerator keys include the TAB, END, and HOME keys.

RESOLUTION

The problem can be resolved by adding the following code to your MFC ActiveX Control. This code forwards the Accelerator Key messages onto your MFC ActiveX Control:

   // Trap keys and forward on to the control.
   BOOL CMyEditCtrl::PreTranslateMessage(MSG* pMsg)
   {
      switch (pMsg->message)
      {
         case WM_KEYDOWN:
         case WM_KEYUP:
            switch (pMsg->wParam)
            {
               case VK_UP:
               case VK_DOWN:
               case VK_LEFT:
               case VK_RIGHT:
               case VK_HOME:
               case VK_END:
                  SendMessage (pMsg->message, pMsg->wParam, pMsg->lParam);
                  // Windowless controls won't be able to call SendMessage.
                  // Instead, just respond to the message here.
                  return TRUE;
            }
            break;
      }
      return COleControl::PreTranslateMessage(pMsg);
   }

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Using the MFC ActiveX Control Wizard, create a MFC control that subclasses an Edit Control.

2. Compile the .ocx.

3. Add this MFC ActiveX .ocx to a Visual Basic form and run the project.

4. Type some text in the Edit Control and attempt to use the ARROW keys to navigate through the typed text. The ARROW keys are not recognized.

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q168777
   TITLE     : PRB: MFC ActiveX Control in IE Doesn't Detect Keystrokes

Keywords          : vb5all VBKBAX
Version           : WINDOWS:5.0,97; WINNT:5.0
Platform          : WINDOWS winnt
Issue type        : kbprb