fixed a bug when rapidly slidingUp and Down
fixed a bug when rapidly slidingUp and Down

R-J/elefant,AxorB/elefant,jbroadway/elefant,AxorB/elefant,jbroadway/elefant,evan70/elefant,Open343/elefant,jbroadway/elefant,twheel/elefant,AxorB/elefant,Open343/elefant,evan70/elefant,R-J/elefant,jbroadway/elefant,twheel/elefant,twheel/elefant,R-J/elefant,Open343/elefant,evan70/elefant