C / C++ / MFC

// externaly defined.

extern 		CFont fArial,fArial1;

enum { CDF_CENTER, CDF_TOPLEFT, CDF_NONE };

void ChangeDialogFont(CWnd* pWnd, CFont* pFont, int nFlag)
{
	CRect windowRect;

	// grab old and new text metrics
	TEXTMETRIC tmOld, tmNew;
	CDC * pDC = pWnd->GetDC();
	CFont * pSavedFont = pDC->SelectObject(pWnd->GetFont());
	pDC->GetTextMetrics(&tmOld);
	pDC->SelectObject(pFont);
	pDC->GetTextMetrics(&tmNew);
	
	//pDC->SelectObject(pSavedFont);
	pDC->SelectObject(&fArial);

	pWnd->ReleaseDC(pDC);

	long oldHeight = tmOld.tmHeight+tmOld.tmExternalLeading;
	long newHeight = tmNew.tmHeight+tmNew.tmExternalLeading;

	if (nFlag != CDF_NONE)
	{
		// calculate new dialog window rectangle
		CRect clientRect, newClientRect, newWindowRect;

		pWnd->GetWindowRect(windowRect);
		pWnd->GetClientRect(clientRect);
		long xDiff = windowRect.Width() - clientRect.Width();
		long yDiff = windowRect.Height() - clientRect.Height();
	
		newClientRect.left = newClientRect.top = 0;
		newClientRect.right = clientRect.right * tmNew.tmAveCharWidth / tmOld.tmAveCharWidth;
		newClientRect.bottom = clientRect.bottom * newHeight / oldHeight;

		if (nFlag == CDF_TOPLEFT) // resize with origin at top/left of window
		{
			newWindowRect.left = windowRect.left;
			newWindowRect.top = windowRect.top;
			newWindowRect.right = windowRect.left + newClientRect.right + xDiff;
			newWindowRect.bottom = windowRect.top + newClientRect.bottom + yDiff;
		}
		else if (nFlag == CDF_CENTER) // resize with origin at center of window
		{
			newWindowRect.left = windowRect.left - 
							(newClientRect.right - clientRect.right)/2;
			newWindowRect.top = windowRect.top -
							(newClientRect.bottom - clientRect.bottom)/2;
			newWindowRect.right = newWindowRect.left + newClientRect.right + xDiff;
			newWindowRect.bottom = newWindowRect.top + newClientRect.bottom + yDiff;
		}
		pWnd->MoveWindow(newWindowRect);
	}

	pWnd->SetFont(pFont);

	// iterate through and move all child windows and change their font.
	CWnd* pChildWnd = pWnd->GetWindow(GW_CHILD);

	while (pChildWnd)
	{
		pChildWnd->SetFont(pFont);
		pChildWnd->GetWindowRect(windowRect);

		CString strClass;
		::GetClassName(pChildWnd->m_hWnd, strClass.GetBufferSetLength(32), 31);
		strClass.MakeUpper();
		if(strClass==_T("COMBOBOX"))
		{
			CRect rect;
			pChildWnd->SendMessage(CB_GETDROPPEDCONTROLRECT,0,(LPARAM) &rect);
			windowRect.right = rect.right;
			windowRect.bottom = rect.bottom;
		}

		pWnd->ScreenToClient(windowRect);
		windowRect.left = windowRect.left * tmNew.tmAveCharWidth / tmOld.tmAveCharWidth;
		windowRect.right = windowRect.right * tmNew.tmAveCharWidth / tmOld.tmAveCharWidth;
		windowRect.top = windowRect.top * newHeight / oldHeight;
		windowRect.bottom = windowRect.bottom * newHeight / oldHeight;
		pChildWnd->MoveWindow(windowRect);
		
		pChildWnd = pChildWnd->GetWindow(GW_HWNDNEXT);
	}
}

than on OnInitDialog() function

//where 	RECT m_rctPage;
//	CFont m_fntPage;



		fArial.CreateFont(
		16,							// nHeight
		0,							// nWidth
		0,							// nEscapement
		0,							// nOrientation
		FW_BOLD,					// nWeight
		FALSE,						// bItalic
		FALSE,						// bUnderline
		0,							// cStrikeOut
		ANSI_CHARSET,				// nCharSet
		OUT_DEFAULT_PRECIS,			// nOutPrecision
		CLIP_DEFAULT_PRECIS,		// nClipPrecision
		DEFAULT_QUALITY,			// nQuality
		DEFAULT_PITCH | FF_SWISS,	// nPitchAndFamily
		_T("Verdana"));  


	fArial1.CreateFont(
		13,							// nHeight
		0,							// nWidth
		0,							// nEscapement
		0,							// nOrientation
		FALSE,					// nWeight
		FALSE,						// bItalic
		FALSE,						// bUnderline
		0,							// cStrikeOut
		ANSI_CHARSET,				// nCharSet
		OUT_DEFAULT_PRECIS,			// nOutPrecision
		CLIP_DEFAULT_PRECIS,		// nClipPrecision
		DEFAULT_QUALITY,			// nQuality
		DEFAULT_PITCH | FF_SWISS,	// nPitchAndFamily
		_T("Verdana"));  

//--------------------------for set font------------------------------//
	// get the font for the first active page
	CPropertyPage* pPage = GetActivePage ();
	ASSERT (pPage);

	// change the font for the sheet
	
	//ChangeDialogFont (this, &m_fntPage, CDF_CENTER);
	ChangeDialogFont (this, &fArial1, CDF_CENTER);

	// change the font for each page
	for (int iCntr = 0; iCntr < GetPageCount (); iCntr++)
	{
		VERIFY (SetActivePage (iCntr));
		CPropertyPage* pPage = GetActivePage ();
		ASSERT (pPage);
		//ChangeDialogFont (pPage, &m_fntPage, CDF_CENTER);

		ChangeDialogFont (pPage, &fArial1, CDF_CENTER);
	}

	VERIFY (SetActivePage (pPage));

	// set and save the size of the page
	CTabCtrl* pTab = GetTabControl ();
	ASSERT (pTab);

	if (m_psh.dwFlags & PSH_WIZARD)
	{
		pTab->ShowWindow (SW_HIDE);
		GetClientRect (&m_rctPage);

		CWnd* pButton = GetDlgItem (ID_WIZBACK);
		ASSERT (pButton);
		CRect rc;
		pButton->GetWindowRect (&rc);
		ScreenToClient (&rc);
		m_rctPage.bottom = rc.top-2;
	}
	else
	{
		pTab->GetWindowRect (&m_rctPage);
		ScreenToClient (&m_rctPage);
		pTab->AdjustRect (FALSE, &m_rctPage);
	}

	// resize the page	
	pPage->MoveWindow (&m_rctPage);
//--------------------------for set font-------------------------------------//