diff --git a/Src/Common/MDITabBar.cpp b/Src/Common/MDITabBar.cpp
index 07ab550b4e0..e7bfd3ceda7 100644
--- a/Src/Common/MDITabBar.cpp
+++ b/Src/Common/MDITabBar.cpp
@@ -623,11 +623,7 @@ void CMyTabCtrl::UpdateToolTips(int nTabItemIndex)
 BOOL CMDITabBar::Update(bool bOnTitleBar, bool bMaximized)
 {
 	m_bOnTitleBar = bOnTitleBar;
-	m_bMaximized = bMaximized;
-	CRect rc;
-	if (m_bMaximized)
-		AfxGetMainWnd()->GetWindowRect(&rc);
-	m_top = rc.top;
+	m_titleBar.SetMaximized(bMaximized);
 	m_tabCtrl.SetOnTitleBar(bOnTitleBar);
 	return true;
 }
@@ -689,7 +685,7 @@ CSize CMDITabBar::CalcFixedLayout(BOOL bStretch, BOOL bHorz)
 	auto pointToPixel = [lpx](int point) { return MulDiv(point, lpx, 72); };
 	const int pd = pointToPixel(RR_PADDING);
 	const int sw = pointToPixel(RR_SHADOWWIDTH);
-	int my = m_bOnTitleBar ? (m_bMaximized ? (-m_top + 2) : 2) : 0;
+	int my = m_bOnTitleBar ? (m_titleBar.GetTopMargin() + 2) : 0;
 	CSize size(SHRT_MAX, my + tm.tmHeight + (sw + pd) * 2);
 	return size;
 }
@@ -739,12 +735,12 @@ void CMDITabBar::OnNcRButtonUp(UINT nHitTest, CPoint point)
 void CMDITabBar::OnSize(UINT nType, int cx, int cy)
 {
 	__super::OnSize(nType, cx, cy);
-	m_titleBar.OnSize(m_bMaximized, cx, cy);
+	m_titleBar.SetSize(cx, cy);
 	if (m_tabCtrl.m_hWnd)
 	{
 		const int leftMargin = m_bOnTitleBar ? m_titleBar.GetLeftMargin() : 0;
 		const int rightMargin = m_bOnTitleBar ? m_titleBar.GetRightMargin() : 0;
-		const int topMargin = ((m_bMaximized && m_bOnTitleBar) ? -m_top : 0) + (m_bOnTitleBar ? 1 : 0);
+		const int topMargin = ((m_titleBar.GetMaximized() && m_bOnTitleBar) ? m_titleBar.GetTopMargin() : 0) + (m_bOnTitleBar ? 1 : 0);
 		const int bottomMargin = m_bOnTitleBar ? 1 : 0;
 		CSize size{ 0, cy - topMargin - bottomMargin };
 		m_tabCtrl.MoveWindow(leftMargin, topMargin, cx - leftMargin - rightMargin, cy - topMargin - bottomMargin, true);
diff --git a/Src/Common/MDITabBar.h b/Src/Common/MDITabBar.h
index da443034d3e..15456e8acfc 100644
--- a/Src/Common/MDITabBar.h
+++ b/Src/Common/MDITabBar.h
@@ -93,8 +93,6 @@ class CMDITabBar : public CControlBar
 private:
 
 	bool m_bOnTitleBar;
-	bool m_bMaximized;
-	int m_top;
 	CMyTabCtrl m_tabCtrl;
 	CFont m_font;
 	CTitleBarHelper m_titleBar;
@@ -102,8 +100,6 @@ class CMDITabBar : public CControlBar
 public:
 	CMDITabBar()
 		: m_bOnTitleBar(true)
-		, m_bMaximized(false)
-		, m_top(0)
 	{}
 	virtual ~CMDITabBar() {}
 	BOOL Update(bool bOnTitleBar, bool bMaxmized);
diff --git a/Src/TitleBarHelper.cpp b/Src/TitleBarHelper.cpp
index 01bd2a1be2f..6386e85979d 100644
--- a/Src/TitleBarHelper.cpp
+++ b/Src/TitleBarHelper.cpp
@@ -26,6 +26,12 @@ void CTitleBarHelper::Init(CWnd *pWnd)
 	m_pWnd = pWnd;
 }
 
+int CTitleBarHelper::GetTopMargin() const
+{
+	return m_maximized ?
+		GetSystemMetrics(SM_CYFRAME) + GetSystemMetrics(SM_CXPADDEDBORDER) : 0;
+}
+
 void CTitleBarHelper::DrawIcon(CWnd* pWnd, CDC& dc)
 {
 	HICON hIcon = (HICON)pWnd->SendMessage(WM_GETICON, ICON_SMALL2, 0);
@@ -33,7 +39,7 @@ void CTitleBarHelper::DrawIcon(CWnd* pWnd, CDC& dc)
 		hIcon = (HICON)GetClassLongPtr(pWnd->m_hWnd, GCLP_HICONSM);
 	if (hIcon == nullptr)
 		return;
-	const int topMargin = (m_maximized ? -m_rc.top : 0);
+	const int topMargin = GetTopMargin();
 	const int height = m_size.cy - topMargin;
 	const int cx = PointToPixel(12.f);
 	const int cy = PointToPixel(12.f);
@@ -123,18 +129,16 @@ CRect CTitleBarHelper::GetButtonRect(int button) const
 {
 	CRect rcPart;
 	const float buttonWidth = PointToPixelF(m_rightMargin) / 3.f;
-	const int topMargin = (m_maximized ? -m_rc.top : 0);
-	rcPart.top = topMargin;
+	rcPart.top = GetTopMargin();
 	rcPart.bottom = m_size.cy;
 	rcPart.left = static_cast<int>(m_size.cx - (3 - button) * buttonWidth);
 	rcPart.right = static_cast<int>(rcPart.left + buttonWidth + 0.5);
 	return rcPart;
 }
 
-void CTitleBarHelper::OnSize(bool maximized, int cx, int cy)
+void CTitleBarHelper::SetSize(int cx, int cy)
 {
 	m_size = CSize(cx, cy);
-	m_maximized = maximized;
 	CClientDC dc(m_pWnd);
 	m_dpi = dc.GetDeviceCaps(LOGPIXELSX);
 	m_pWnd->GetWindowRect(&m_rc);
diff --git a/Src/TitleBarHelper.h b/Src/TitleBarHelper.h
index 6d6720cad7a..eb091e1fdef 100644
--- a/Src/TitleBarHelper.h
+++ b/Src/TitleBarHelper.h
@@ -16,10 +16,13 @@ class CTitleBarHelper {
 	void Init(CWnd* pWnd);
 	void DrawIcon(CWnd* pWnd, CDC& dc);
 	void DrawButtons(CDC& dc, COLORREF textColor, COLORREF backColor);
+	int GetTopMargin() const;
 	int GetLeftMargin() const { return PointToPixel(m_leftMargin); }
 	int GetRightMargin() const { return PointToPixel(m_rightMargin); }
 	CRect GetButtonRect(int button) const;
-	void OnSize(bool maximized, int cx, int cy);
+	void SetMaximized(bool maximized) { m_maximized = maximized; }
+	bool GetMaximized() const { return m_maximized; }
+	void SetSize(int cx, int cy);
 	LRESULT OnNcHitTest(CPoint pt);
 	void OnNcMouseMove(UINT nHitTest, CPoint point);
 	void OnNcMouseLeave();