Implement AbstractClient::isFirstInTabBox

Moves implementation from Client to AbstractClient. Setter is protected,
getter is no longer virtual.

abstract_client.h

@@ -48,12 +48,14 @@ public:
     QWeakPointer<TabBox::TabBoxClientImpl> tabBoxClient() const {
         return m_tabBoxClient.toWeakRef();
     }
+    bool isFirstInTabBox() const {
+        return m_firstInTabBox;
+    }
 
     virtual void updateMouseGrab();
     virtual QString caption(bool full = true, bool stripped = false) const = 0;
     virtual bool isMinimized() const = 0;
     virtual bool isCloseable() const = 0;
-    virtual bool isFirstInTabBox() const = 0;
     // TODO: remove boolean trap
     virtual bool isShown(bool shaded_is_shown) const = 0;
     virtual bool wantsTabFocus() const = 0;
@@ -165,11 +167,15 @@ public Q_SLOTS:
 
 protected:
     AbstractClient();
+    void setFirstInTabBox(bool enable) {
+        m_firstInTabBox = enable;
+    }
     // TODO: remove boolean trap
     virtual bool belongsToSameApplication(const AbstractClient *other, bool active_hack) const = 0;
 
 private:
     QSharedPointer<TabBox::TabBoxClientImpl> m_tabBoxClient;
+    bool m_firstInTabBox = false;
 };
 
 }

client.cpp

@@ -131,7 +131,6 @@ Client::Client()
     , pending_geometry_update(PendingGeometryNone)
     , shade_geometry_change(false)
     , sm_stacking_order(-1)
-    , m_firstInTabBox(false)
     , electricMaximizing(false)
     , activitiesDefined(false)
     , needsSessionInteract(false)

client.h

@@ -607,12 +607,6 @@ public:
 
     void layoutDecorationRects(QRect &left, QRect &top, QRect &right, QRect &bottom) const;
 
-    bool isFirstInTabBox() const override {
-        return m_firstInTabBox;
-    }
-    void setFirstInTabBox(bool enable) {
-        m_firstInTabBox = enable;
-    }
     Xcb::Property fetchFirstInTabBox() const;
     void readFirstInTabBox(Xcb::Property &property);
     void updateFirstInTabBox();
@@ -969,7 +963,6 @@ private:
     int sm_stacking_order;
     friend struct ResetupRulesProcedure;
     friend class GeometryUpdatesBlocker;
-    bool m_firstInTabBox;
 
     bool electricMaximizing;
     QuickTileMode electricMode;