PRB: Windowless ATL Control Does Not Receive Focus Messages in Internet Explorer (318034)

MORE INFORMATION

• IOleInPlaceObject::UIDeactivate is called if you press TAB or click another control in Internet Explorer. This is where you can handle the equivalent of a WM_KILLFOCUS event.
• IOleObject::DoVerb is called with OLEIVERB_UIACTIVATE if you press TAB or click your control. You must not call IOleInPlaceSiteWindowless::SetFocus(TRUE) from here because that function calls the DoVerb method and causes a stack overflow.
• IOleInPlaceActiveObject::OnFrameWindowActivate is called on the user interface (UI) active control whenever the hosting application switches in and out of focus. If you want to receive keyboard messages, you must call IOleInPlaceSiteWindowless::SetFocus(TRUE) when your control is being activated.
• The OnKeyDown function is added to demonstrate when the keyboard messages are received.
• The OnLButtonDown function is added to show that you must call the SetFocus method when you click the control. If you do not call SetFocus, you do not receive keyboard messages.

class ATL_NO_VTABLE CAtlFocusTest : 
...
{
public:
...
	STDMETHOD(UIDeactivate)(void)
	{
		ATLTRACE("CAtlFocusTest::UIDeactivate() - handle kill focus event\n");
		return IOleInPlaceObjectWindowlessImpl<CAtlFocusTest>::UIDeactivate();
	}

	STDMETHOD(DoVerb)(LONG iVerb, LPMSG pMsg, IOleClientSite* pActiveSite, LONG lindex,
									 HWND hwndParent, LPCRECT lprcPosRect)
	{
		if (iVerb == OLEIVERB_UIACTIVATE)
		{
			ATLTRACE("CAtlFocusTest::DoVerb(iVerb=%d) - handle set focus event\n", iVerb);
			// Do not call IOleInPlaceSiteWindowless::SetFocus(TRUE) here because
			// it will call DoVerb again!
		}
		else
			ATLTRACE("CAtlFocusTest::DoVerb(iVerb=%d) - handle some other event\n", iVerb);
		return IOleObjectImpl<CAtlFocusTest>::DoVerb(iVerb, pMsg, pActiveSite, lindex, hwndParent, lprcPosRect);
	}

	STDMETHOD(OnFrameWindowActivate)(BOOL fActivate)
	{
		if (fActivate)
		{
			ATLTRACE("CAtlFocusTest::OnFrameWindowActivate(fActivate=%d) - handle set focus event (switching app)\n", fActivate);
			if (m_spInPlaceSite)
				m_spInPlaceSite->SetFocus(TRUE);
		}
		else
		{
			ATLTRACE("CAtlFocusTest::OnFrameWindowActivate(fActivate=%d) - handle kill focus event (switching app)\n", fActivate);
			if (m_spInPlaceSite)
				m_spInPlaceSite->SetFocus(FALSE);
		}
		return IOleInPlaceActiveObjectImpl<CAtlFocusTest>::OnFrameWindowActivate(fActivate);
	}
	LRESULT OnKeyDown(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
	{
		ATLTRACE("CAtlFocusTest::OnKeyDown(%d, %d, %d, %d)\n",
			uMsg, wParam, lParam, bHandled);
		return 0;
	}
	LRESULT OnLButtonDown(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
	{
		if (m_spInPlaceSite)
			m_spInPlaceSite->SetFocus(TRUE);
		return 0;
	}
...
};