can someone help - OnSize and SetWindowPos?

[JohnCz]

DO NOT call OnSize directly
It is a message handler for handling WM_SIZE message. It will not do any harm in this case but it creates a habbit of calling handlers and you can do harm doing that.

CFormView class does not have OnInitDialog. OnInitDialog is also a part of a message handler but is handled differently in a CDialog class and CFormView class.

Your algorithm is based on original position of the control in a resource editor. Use dimentions that are delivered by system to a OnSize handler. You should change code to something like that:

	CFormView::OnSize(nType, cx, cy);
	
	CWnd *pEditWnd = GetDlgItem(IDC_EDIT);

	CWnd *pREditWnd = GetDlgItem(IDC_RICHEDIT);
	
	if(IsWindow(*pEditWnd) && IsWindow(*pREditWnd))
	{
		int iHeightRatio = cy / 3;
		pREditWnd->SetWindowPos(NULL,
			5, 
			5,
			cx - 10 , 
			cy / 3 , 
			SWP_NOZORDER );
		
		
		pREditWnd->GetWindowRect(RectRICHEDIT);
		ScreenToClient(&RectRICHEDIT);
		
		
		pEditWnd->SetWindowPos(NULL, 
			5, 
			iHeightRatio + 3,
			cx - 10 , 
			cy - iHeightRatio - 13,
			SWP_NOZORDER);
		
	}

Above will position both windows with margins of 5 pixels from each side of the splitter.

As you can see, I have changed parts of your code:

Do not pass NULL to a SetWindowPos. At least pass SWP_NOZORDER, if you want to move and resize controls. In general: use flags to tell SetWindowPos what you want to do.

Do not use GetDlgItem(IDC_EDIT)->CallSomeFunction. You do not know if GetDlgItem will return a valid pointer. If not, you are cooked; your application will crash. Also, you are calling function three times while assigning return value to a local variable requires only one call.

You mau be better off using BeginDeferWindowPos , DeferWindowPos, EndDeferWindowPos:

	CFormView::OnSize(nType, cx, cy);
	
	CWnd *pEditWnd = GetDlgItem(IDC_EDIT);
	CWnd *pREditWnd = GetDlgItem(IDC_RICHEDIT);

	if(IsWindow(*pEditWnd) && IsWindow(*pREditWnd))
	{
		HDWP hDwp = BeginDeferWindowPos(2);
		
		int iHeightRatio = cy / 3;

		hDwp = DeferWindowPos(hDwp, *pEditWnd, NULL, 
					5, 
					5,
					cx - 10, 
					cy / 3,
					SWP_NOZORDER);
		
		
		hDwp = DeferWindowPos(hDwp, *pREditWnd, NULL, 
					5, 
					iHeightRatio + 5,
					cx - 10 , 
					cy - iHeightRatio - 15,
					SWP_NOZORDER );

		// move all at once
		EndDeferWindowPos(hDwp);
		
	}

You may want to change calculations as you need but general idea is there.