Highlight view with focus

NOTE: This uses an undocumented feature in MFC so be careful in the future.

Step 1) Derive your own SplitterWnd class.
Step 2) Override the undocumented OnDrawSplitter function.
Step 3) Replace the CSplitterWnd instance in the child frame with your splitter.

This example draws in red but you can adjust the color and width of the frame by altering the define values.

///////////////////////////////////////////////////////////////////////////// 
// MySplitterWnd.h

class MySplitterWnd : public CSplitterWnd
{
public: 
	int cRow;
	int cCol; 
	MySplitterWnd();
	void OnDrawSplitter(CDC* pDC, ESplitType nType,
		const CRect& rectArg);
	void RefreshSplitBars(void);
};



///////////////////////////////////////////////////////////////////////////// 
// MySplitterWnd.cpp

#include "StdAfx.h"
#include "MySplitterWnd.h"

#define FOCUS_HILIGHT_COLOR_ULO RGB(180, 75, 25)
#define FOCUS_HILIGHT_COLOR_LRO RGB(245, 5, 25)
#define FOCUS_HILIGHT_COLOR_ULI RGB(145, 95, 75)
#define FOCUS_HILIGHT_COLOR_LRI RGB(220, 65, 40)

#define FOCUS_HILIGHT_SHOW TRUE

#define SPLITTER_CX 4
#define SPLITTER_CY 4
#define SPLITTER_GAPX 4
#define SPLITTER_GAPY 4

void MySplitterWnd::RefreshSplitBars(void)
{
	CRect rectInside;

	GetInsideRect(rectInside);
	DrawAllSplitBars(NULL, rectInside.right, rectInside.bottom);
}


MySplitterWnd::MySplitterWnd()
{
	cRow = 0;
	cCol = 0; 
	
	m_cxSplitter = SPLITTER_CX;
	m_cySplitter = SPLITTER_CY;
	m_cxSplitterGap = SPLITTER_GAPX;
	m_cySplitterGap = SPLITTER_GAPY;
}


void MySplitterWnd::OnDrawSplitter(CDC* pDC, ESplitType nType, const CRect& rectArg)
{
	if((FOCUS_HILIGHT_SHOW) && ((GetRowCount()>1) || (GetColumnCount()>1)) && (nType == splitBorder))
	{
		int pRow = 0;
		int pCol = 0;
		if(rectArg.top)
		{
			pRow = 1;
		}
		if(rectArg.left)
		{
			pCol = 1;
		}
		if((cRow == pRow) && (cCol == pCol))
		{
			if (pDC == NULL)
			{
				RedrawWindow(rectArg, NULL, RDW_INVALIDATE|RDW_NOCHILDREN);
				return; 
			}
			ASSERT_VALID(pDC);
			CRect rect = rectArg;
			pDC->Draw3dRect(rect, FOCUS_HILIGHT_COLOR_ULO, FOCUS_HILIGHT_COLOR_LRO);
			rect.InflateRect(-GetSystemMetrics(SM_CXBORDER), -GetSystemMetrics(SM_CYBORDER));
			pDC->Draw3dRect(rect, FOCUS_HILIGHT_COLOR_ULI, FOCUS_HILIGHT_COLOR_LRI);
			return; 
		}
	}
	
	CSplitterWnd::OnDrawSplitter(pDC,nType,rectArg); 
}