' benötigt:
' 1 Form, 1 Picture
Option Explicit
Dim xa As Integer
Dim ya As Integer
Dim status As String
Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, X As _
  Single, Y As Single)
    If Button = vbLeftButton Then
        status = "zeichnet"
        ' lösche alten Kreis
        Picture1.Circle (xa, ya), 100, Picture1.BackColor
        ' aktueller Kreis
        Picture1.Circle (X, Y), 100, vbRed
        xa = X
        ya = Y
    End If
End Sub
Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, X As Single, _
  Y As Single)
    If status = "zeichnet" Then
        Picture1.Circle (X, Y), 100, vbBlue
        Picture1.PSet (X, Y)
        xa = ya = 0
    End If
End Sub