Option Explicit
 
Private mbFirstClick      As Boolean
Private mlX               As Long
Private mlY               As Long
 
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As _
  Single, Y As Single)
Dim lRadius   As Long
 
  If mbFirstClick Then
    If mlX < X Then
      lRadius = X - mlX
    Else
      lRadius = mlX - X
    End If
    Picture1.Circle (mlX, mlY), lRadius
    mbFirstClick = False
  Else
    mlX = X
    mlY = Y
    mbFirstClick = True
  End If
 
End Sub