PRB: Backspace in ATL Subclassed CTL Causes Internet Explorer to Navigate Back (190044)

The information in this article applies to:

Microsoft Internet Explorer (Programming) 3.02
Microsoft Internet Explorer (Programming) 4.0
Microsoft Internet Explorer (Programming) 4.01
Microsoft Internet Explorer (Programming) 4.01 SP1
Microsoft Internet Explorer (Programming) 5
Microsoft Internet Explorer (Programming) 5.01
Microsoft Internet Explorer (Programming) 5.01 SP1
Microsoft Internet Explorer (Programming) 5.5

This article was previously published under Q190044

SYMPTOMS

When an ATL ActiveX control that subclasses an edit control is hosted in Internet Explorer, pressing the BACKSPACE key when focus is set to the Edit control causes Internet Explorer to navigate to the previous Web page. If there are no Web pages previous to the one with the control, the BACKSPACE key functions as normal.

CAUSE

When the user clicks on the subclassed control, the control is not UI Activated. This means that any accelerator keys are processed by the Internet Explorer frame. The control is never given a change to process the BACKSPACE accelerator key.

RESOLUTION

When the user clicks in the edit box, a WM_MOUSEACTIVATE message is sent to the control. When this message is received, manually activate the control by calling CComControl::InPlaceActivate(OLEIVERB_UIACTIVATE).

Here is sample code for a WM_MOUSEACTIVATE handler that calls InPlaceActivate to manually UI Activate itself:

LRESULT OnMouseActivate(UINT, WPARAM, LPARAM, BOOL&)
{
   // Manually activate the control
   InPlaceActivate(OLEIVERB_UIACTIVATE);

   return 0;
}

STATUS

This behavior is by design.

REFERENCES

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

179696 PRB: Focus and Tab Issues with ATL Subclassed Edit Control

Modification Type:	Major	Last Reviewed:	5/12/2003
Keywords:	kbCtrl kbnofix kbprb KB190044