Custom status messages and tooltips

By default MFC uses string resources with the same ID as the toolbar buttons for status
messages and tooltip text.

Sometimes you might want to change some of these messages or texts in runtime. This
requires a little work. The following explanations are written for MDI.

The easiest first; custom statusbar messages:

For this you must override the GetMessageString function of the CMDIFrameWnd. The
following is an example:

void CMainFrame::GetMessageString(UINT nID, CString& rMessage) const
{
	// load appropriate string
	if(!m_bCustomMessage) {
		CFrameWnd::GetMessageString(nID, rMessage);
		return;
	}

	switch(nID) {
	case ID_LOOK_UP:
		rMessage = _T("Look out");
		break;
	case ID_LOOK_DOWN:
		rMessage = _T("Look down");
		break;
	default:
		CFrameWnd::GetMessageString(nID, rMessage);
	}
}

Instead of hardcoding the messages, other string resources than the default can be
loaded and assigned. This above functionality works also for menus.

Now for something slightly more difficult; custom tooltip text. I had to dig a little
for this. To override the default tooltip text handling two messages must be intercepted
in the CMDIChildFrame, namely TTN_NEEDTEXTW and TTN_NEEDTEXTA. One of these (depending on
unicode/not unicode) is sent when tooltip text is needed for a toolbar button.

BEGIN_MESSAGE_MAP(CMyChildFrame, CMDIChildWnd)
//{{AFX_MSG_MAP(CNetbasChildFrame)
ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTW, 0, 0xFFFF, OnToolTipText)
ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTA, 0, 0xFFFF, OnToolTipText)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMyChildFrame message handlers
BOOL CMyChildFrame::GetToolText( UINT nID, CString& strTipText )
{
	switch(nID) {
	case ID_LOOK_UP:
		strTipText = _T("Tip out");
		return TRUE;
	case ID_LOOK_DOWN:
		strTipText = _T("Tip down");
		return TRUE;
	}
	return FALSE;
}

#define _countof(array) (sizeof(array)/sizeof(array[0]))

BOOL CMyChildFrame::OnToolTipText(UINT nID, NMHDR* pNMHDR,
								  LRESULT*pResult)
{
	ASSERT(pNMHDR->code == TTN_NEEDTEXTA || pNMHDR->code == TTN_NEEDTEXTW);

	TOOLTIPTEXTA* pTTTA = (TOOLTIPTEXTA*)pNMHDR;
	TOOLTIPTEXTW* pTTTW = (TOOLTIPTEXTW*)pNMHDR;

	CString strTipText;
	if ( GetToolText( pNMHDR->idFrom, strTipText ) )
	{
#ifndef _UNICODE
		if (pNMHDR->code == TTN_NEEDTEXTA)
			lstrcpyn(pTTTA->szText, strTipText, _countof(pTTTA->szText));
		else
			_mbstowcsz(pTTTW->szText, strTipText, _countof(pTTTW->szText));
#else
		if (pNMHDR->code == TTN_NEEDTEXTA)
			_wcstombsz(pTTTA->szText, strTipText, _countof(pTTTA->szText));
		else
			lstrcpyn(pTTTW->szText, strTipText, _countof(pTTTW->szText));
#endif
		return TRUE;
	}

	return CMDIChildWnd::OnToolTipText( nID, pNMHDR, pResult );
}

Here I have implemented a helper function that checks if we want to override the given
button. In that case we assign a tooltip text. Otherwise we let the message pass through.