Remove virtual inheritance from the codebase, refs 6b51d71c85, e21ebb37f5 e326ebae46.

Remove workaround in 3d07327837 / D2136, the pointer from IGUIObject to
IGUITextOwner that avoided the dynamic_cast.
Have the GUIObject implementing class take responsibility of calling the
virtual methods in the base classes.
Leaves the code in a clean state that can serve as an example for new
GUI object classes, such as D1346, refs #4683.

Differential Revision: https://code.wildfiregames.com/D2325
Comments By: Vladislav on IRC 2019-07-30, 2019-08-22, 2019-09-20-23
Tested on: clang 8.0.1, Jenkins

This was SVN commit r23020.

source/gui/IGUIButtonBehavior.h

@@ -35,10 +35,12 @@ class CGUISpriteInstance;
  * Can be used with multiple inheritance alongside
  * IGUISettingsObject and such.
  */
-class IGUIButtonBehavior : virtual public IGUIObject
+class IGUIButtonBehavior
 {
+	NONCOPYABLE(IGUIButtonBehavior);
+
 public:
-	IGUIButtonBehavior(CGUI& pGUI);
+	IGUIButtonBehavior(IGUIObject& pObject);
 	virtual ~IGUIButtonBehavior();
 
 	/**
@@ -61,13 +63,7 @@ protected:
 	/**
 	 * @see IGUIObject#ResetStates()
 	 */
-	virtual void ResetStates()
-	{
-		// Notify the gui that we aren't hovered anymore
-		UpdateMouseOver(nullptr);
-		m_Pressed = false;
-		m_PressedRight = false;
-	}
+	virtual void ResetStates();
 
 	/**
 	 * Everybody knows how a button works, you don't simply press it,
@@ -85,6 +81,13 @@ protected:
 	CStrW m_SoundLeave;
 	CStrW m_SoundPressed;
 	CStrW m_SoundReleased;
+
+private:
+	/**
+	 * Reference to the IGUIObject.
+	 * Private, because we don't want to inherit it in multiple classes.
+	 */
+	IGUIObject& m_pObject;
 };
 
 #endif // INCLUDED_IGUIBUTTONBEHAVIOR