Bug? Adding Button via Code to a Pane has fixed width/height

Sub CreateCharMatrix
    Dim btn As Button
    btn.Initialize("btn")
    btn.Tag = "1"
    MainForm.RootPane.AddNode(btn, 20, 20, 10, 10)

    Dim btn As Button
    btn.Initialize("btn")
    btn.Tag = "2"
    MainForm.RootPane.AddNode(btn, 20, 80, 20, 20)
End Sub

For j = 1 To 25
    For i = 1 To 25
        Dim b As Button
        b.Initialize("b")
        MainForm.RootPane.AddNode(b, i*30, j*30, i, j)
    Next
Next

'define the button and add to the rootpane of the mainform
Dim btn As Button
btn.Initialize("btn")
btn.Text = "Button 1"
'h and w must have initial value > 0
MainForm.RootPane.AddNode(btn, 20,20, 1, 1)
Dim jo As JavaObject = btn
Dim h As Double = 15.0
Dim w As Double = 15.0
jo.RunMethod("setMinSize", Array(h, w))