Add virtual AbstractClient::showContextHelp and ::providesContextHelp

Required in the context of decorations. Default implementation does
nothing respectively returns false.

abstract_client.cpp

@@ -1461,4 +1461,13 @@ void AbstractClient::startDecorationDoubleClickTimer()
     m_decorationDoubleClickTimer.start();
 }
 
+bool AbstractClient::providesContextHelp() const
+{
+    return false;
+}
+
+void AbstractClient::showContextHelp()
+{
+}
+
 }

abstract_client.h

@@ -213,6 +213,11 @@ class KWIN_EXPORT AbstractClient : public Toplevel
      * If this property gets abused by application developers, it will be removed again.
      **/
     Q_PROPERTY(bool noBorder READ noBorder WRITE setNoBorder)
+    /**
+     * Whether the Client provides context help. Mostly needed by decorations to decide whether to
+     * show the help button or not.
+     **/
+    Q_PROPERTY(bool providesContextHelp READ providesContextHelp CONSTANT)
 public:
     virtual ~AbstractClient();
 
@@ -511,6 +516,26 @@ public:
     bool processDecorationButtonPress(QMouseEvent *event, bool ignoreMenu = false);
     void processDecorationButtonRelease(QMouseEvent *event);
 
+    /**
+    * Returns whether the window provides context help or not. If it does,
+    * you should show a help menu item or a help button like '?' and call
+    * contextHelp() if this is invoked.
+    *
+    * Default implementation returns @c false.
+    * @see showContextHelp;
+    */
+    virtual bool providesContextHelp() const;
+
+    /**
+    * Invokes context help on the window. Only works if the window
+    * actually provides context help.
+    *
+    * Default implementation does nothing.
+    *
+    * @see providesContextHelp()
+    */
+    virtual void showContextHelp();
+
     // TODO: remove boolean trap
     static bool belongToSameApplication(const AbstractClient* c1, const AbstractClient* c2, bool active_hack = false);
 

client.h

@@ -89,11 +89,6 @@ class Client
      * @see moveable
      **/
     Q_PROPERTY(bool moveableAcrossScreens READ isMovableAcrossScreens)
-    /**
-     * Whether the Client provides context help. Mostly needed by decorations to decide whether to
-     * show the help button or not.
-     **/
-    Q_PROPERTY(bool providesContextHelp READ providesContextHelp CONSTANT)
     /**
      * Whether the Client can be resized. The property is evaluated each time it is invoked.
      * Because of that there is no notify signal.
@@ -236,7 +231,7 @@ public:
     void resizeWithChecks(const QSize& s, xcb_gravity_t gravity, ForceGeometry_t force = NormalGeometrySet);
     QSize sizeForClientSize(const QSize&, Sizemode mode = SizemodeAny, bool noframe = false) const override;
 
-    bool providesContextHelp() const;
+    bool providesContextHelp() const override;
     const QKeySequence &shortcut() const override;
     void setShortcut(const QString& cut) override;
 
@@ -286,7 +281,7 @@ public:
 
     void killWindow();
     void toggleShade();
-    void showContextHelp();
+    void showContextHelp() override;
     void cancelShadeHoverTimer();
     void checkActiveModal();
     StrutRect strutRect(StrutArea area) const;