有一个名称为Form1的窗体,上面没有控件,没有以下程序(其中方法Pset(X,Y)的功能是在坐标X,Y处画一个点): Dim cmdmave As Boolean Private Sub Form_MouseDown(Button As Integer,Shift As Integer,X As Single,Y As Single) cmdmave=True End Sub Private Sub Form_MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single) If cmdmave Then Form1.Pset(X,Y) End If End Sub Private Sub Form_MouseUp(Button As Integer,Shift As Integer,X As Single,Y As Single) cmdmave=False End Sub 此程序的功能是( )