Sets the current action for this widget that highlights the size
        for this toolbar.
        
        :param      action | <QAction>

def setCurrentAction(self, action):
        """
        Sets the current action for this widget that highlights the size
        for this toolbar.
        
        :param      action | <QAction>
        """
        if action == self._currentAction:
            return
        
        self._currentAction = action
        self.currentActionChanged.emit(action)
        
        labels   = self.actionLabels()
        anim_grp = QParallelAnimationGroup(self)
        max_size = self.maximumPixmapSize()
        min_size = self.minimumPixmapSize()
        
        if action:
            label = self.labelForAction(action)
            index = labels.index(label)
            
            # create the highlight effect
            palette = self.palette()
            effect = QGraphicsDropShadowEffect(label)
            effect.setXOffset(0)
            effect.setYOffset(0)
            effect.setBlurRadius(20)
            effect.setColor(QColor(40, 40, 40))
            label.setGraphicsEffect(effect)
            
            offset = self.padding()
            if self.position() in (XDockToolbar.Position.East,
                                   XDockToolbar.Position.West):
                self.resize(max_size.width() + offset, self.height())
            
            elif self.position() in (XDockToolbar.Position.North,
                                     XDockToolbar.Position.South):
                self.resize(self.width(), max_size.height() + offset)
            
            w  = max_size.width()
            h  = max_size.height()
            dw = (max_size.width() - min_size.width()) / 3
            dh = (max_size.height() - min_size.height()) / 3
            
            for i in range(4):
                before = index - i
                after  = index + i
                
                if 0 <= before and before < len(labels):
                    anim = XObjectAnimation(labels[before],
                                            'setPixmapSize',
                                            anim_grp)
                    
                    anim.setEasingCurve(self.easingCurve())
                    anim.setStartValue(labels[before].pixmapSize())
                    anim.setEndValue(QSize(w, h))
                    anim.setDuration(self.duration())
                    anim_grp.addAnimation(anim)
                    
                    if i:
                        labels[before].setGraphicsEffect(None)
                
                if after != before and 0 <= after and after < len(labels):
                    anim = XObjectAnimation(labels[after],
                                            'setPixmapSize',
                                            anim_grp)
                    
                    anim.setEasingCurve(self.easingCurve())
                    anim.setStartValue(labels[after].pixmapSize())
                    anim.setEndValue(QSize(w, h))
                    anim.setDuration(self.duration())
                    anim_grp.addAnimation(anim)
                    
                    if i:
                        labels[after].setGraphicsEffect(None)
            
                w -= dw
                h -= dh
        else:
            offset = self.padding()
            for label in self.actionLabels():
                # clear the graphics effect 
                label.setGraphicsEffect(None)
                
                # create the animation
                anim = XObjectAnimation(label, 'setPixmapSize', self)
                anim.setEasingCurve(self.easingCurve())
                anim.setStartValue(label.pixmapSize())
                anim.setEndValue(min_size)
                anim.setDuration(self.duration())
                anim_grp.addAnimation(anim)
            
            anim_grp.finished.connect(self.resizeToMinimum)
        
        anim_grp.start()
        self._animating = True
        anim_grp.finished.connect(anim_grp.deleteLater)
        anim_grp.finished.connect(self.__markAnimatingFinished)
        
        if self._currentAction:
            self._hoverTimer.start()
        else:
            self._hoverTimer.stop()