Spanish Cambiar imagen a un botón

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.

    Private pnlSuperior As Panel
    Private TituloTally As Label
    Private scrollTests As ScrollView
    Private pnlBotones As Panel
    Private btnTests As Button
    Private btnPerfil As Button
    Private btnTrabajos As Button
    Private btnCerrarSesion As Button
'    Private lblTextoBotones As Label
    Private imvImage As ImageView
    
End Sub

Sub Activity_Create(FirstTime As Boolean)
'16pf
    txt.Initialize("lbl16pf")
    txt.Text = "Test 16pf"
    txt.TextSize = 28
    txt.TextColor = Colors.White
    txt.Typeface = fuente
    bm.InitializeSample(File.DirAssets, "FondoTestActivo.png", 45%x, 45%y)
    imvImage.Initialize("img16pf")
    imvImage.Bitmap = bm
    bm.InitializeSample(File.DirAssets, "FondoTestActivo.png", 45%x, 45%y)
'3%y es el espaciado entre tests
    scrollTests.Panel.AddView(imvImage, 1%x, 23%y + 3%y, 100%x, 23%y)
    scrollTests.Panel.AddView(txt, 15%x, 28%y, 25%x, 15%y)

' ...
 bm.InitializeSample(File.DirAssets, "FondoTestActivo.png", 45%x, 45%y)
    imvImage.Initialize("img16pf")
    imvImage.Bitmap = bm
    bm.InitializeSample(File.DirAssets, "FondoTestActivo.png", 45%x, 45%y)

dim boton as button
boton.initialize("algunsub")
activity.addview(boton, ...)

sub algunsub_click
   imgview.bitmap = bitmap2
   imgview.invalidate     ' no iría mal este paso
end sub