Private sX As Long
Private sy As Long
 
Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, X As _
  Single, Y As Single)
   If Button = 1 Then
     If sX = 0 And sy = 0 Then sX = X: sy = Y
     Picture1.Line (sX, sy)-(X, Y), RGB(0, 0, 255)
     sX = X: sy = Y
   Else
     sX = 0: sy = 0
   End If
End Sub