程序代码(form3) ◆ Dim trace As Boolean Private Sub Command1 Click ◆Form1.Show ◆ Unload me ◆ End sub Private Sub Form Mouse Down(Button As Integer, Shift As Integer, X As Single, Y AS Single) r= Rnd*800 Ifr< 200 Then r= 200 trace= True Circle (X, Y),r ◆ End sub Private Sub Form MouseUp(Button As Integer, Shift As Integer, XAS Single, Y As Single) trace= False End Sub Dim trace As Boolean  Private Sub Command1_Click()  Form1.Show  Unload Me  End Sub  Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)  r = Rnd * 800  If r < 200 Then r = 200  trace = True  Circle (X, Y), r  End Sub  Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)  trace = False  End Sub 程序代码（form3）