refs #312 navigation bars, contributes also to #347

* allow to set/unset frameless mode in CDockWidget
* adjusted context menus
* adjusted style sheets
* ini settings for margins
* hidden info area to host floating widgets only visible when floating (allows to CDockInfoArea widgets)
* made some private slots non-virtual

src/blackgui/components/invisibleinfoareacomponent.h

@@ -0,0 +1,62 @@
+/* Copyright (C) 2015
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+#ifndef BLACKGUI_COMPONENTS_INVISIBLEINFOAREACOMPONENT_H
+#define BLACKGUI_COMPONENTS_INVISIBLEINFOAREACOMPONENT_H
+
+#include "blackgui/infoarea.h"
+#include <QMainWindow>
+
+namespace Ui { class CInvisibleInfoAreaComponent; }
+
+namespace BlackGui
+{
+    namespace Components
+    {
+
+        //! Info area to carry info areas on visibile when floating
+        class CInvisibleInfoAreaComponent : public BlackGui::CInfoArea
+        {
+            Q_OBJECT
+
+        public:
+
+            //! Info areas
+            enum InfoArea
+            {
+                // index must match tab index!
+                InfoAreaVerticalNavigator   =  0,
+                InfoAreaHorizontalNavigator =  1
+            };
+
+            //! Consturctor
+            explicit CInvisibleInfoAreaComponent(QWidget *parent = nullptr);
+
+            //! Destructor
+            ~CInvisibleInfoAreaComponent();
+
+            //! \copydoc CInfoArea::getPreferredSizeWhenFloating
+            virtual QSize getPreferredSizeWhenFloating(int areaIndex) const override;
+
+            //! \copydoc CInfoArea::indexToPixmap
+            const QPixmap &indexToPixmap(int areaIndex) const override;
+
+        public slots:
+            //! Navigator floating
+            void toggleNavigator();
+
+        private:
+            QScopedPointer<Ui::CInvisibleInfoAreaComponent> ui;
+        };
+
+    } // ns
+} // ns
+
+
+#endif // guard