class CSplitterWnd : public CWnd
{
public:
	int m_cxSplitterGap, m_cySplitterGap;   // amount of space between panes
	virtual void TrackRowSize(int y, int row);
	virtual void TrackColumnSize(int x, int col);
...}

BOOL CMainFrame::OnCreateClient( LPCREATESTRUCT lpcs, CCreateContext* pContext )
{
	GetWindowRect(&rect);
	int width,height;
	width = rect.Width();
	CSplitterWnd splitter;
	height = (rect.Height() + splitter.m_cySplitterGap)/2;
...
}