timer1代码（interval默认为0）：
thisform.image1.top=thisform.image1.top+10
if thisform.image1.top>=thisform.height-thisform.image1.height
   thisform.image1.top=thisform.height-thisform.image1.height
   thisform.timer1.Interval=0
   thisform.timer2.Interval=100
endif
timer2代码（interval默认为0）：
thisform.image1.top=thisform.image1.top-10
IF thisform.image1.Top<=0
thisform.image1.top=0
thisform.timer2.interval=0
thisform.timer1.interval=100
endif
开始 按钮代码：
thisform.timer1.Interval =100