** test.prg
of = CREATEOBJECT("form1")
of.show(1)

DEFINE CLASS form1 AS form
    ADD OBJECT shape1 AS shape WITH Top=10,Left=10,Height=70,Width=70,Curvature=99
    ADD OBJECT timer1 AS timer WITH Interval=500
    mTop = 0
    mLeft = 0
   
    PROCEDURE init
        this.mTop = this.Height - this.shape1.Height
        this.mLeft = this.Width - this.shape1.Width
    ENDPROC
   
    PROCEDURE timer1.Timer
        thisform.shape1.top = INT(thisform.mTop * RAND())
        thisform.shape1.left = INT(thisform.mLeft * RAND())
    ENDPROC
ENDDEFINE

**上面的是.PRG文件，你把上面的保存为 test.prg直接运行

** 如果你是在表单中的，那就这样
** 表单的 INIT中
PUBLIC mTop,mLeft
mTop = thisform.Height - thisform.shape1.Height
mLeft = thisform.Width - thisform.shape1.Width

** 在Timer1.Timer中
thisform.shape1.top = INT(mTop * RAND())
thisform.shape1.left = INT(mLeft * RAND())

解释很详细啊。顺便学习了。