esempio
codice:
Option Explicit
Dim lim_up, lim_down, lim_left, lim_right As Integer

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
Select Case KeyCode
    Case vbKeyUp
        If Shape1.Top <= lim_up Then Exit Sub
        Shape1.Top = Shape1.Top - 10
        
    Case vbKeyDown
        If Shape1.Top >= lim_down - Shape1.Height Then Exit Sub
        Shape1.Top = Shape1.Top + 10
    
    Case vbKeyLeft
        If Shape1.Left <= lim_left Then Exit Sub
        Shape1.Left = Shape1.Left - 10
    
    Case vbKeyRight
        If Shape1.Left >= lim_right - Shape1.Width Then Exit Sub
        Shape1.Left = Shape1.Left + 10
End Select
End Sub

Private Sub Form_Load()
lim_up = Line1.Y1
lim_down = Line2.Y1
lim_left = Line3.X1
lim_right = Line4.X1
End Sub