B4J Question [SOLVED] TabPane opened step-by-step with Buttons - How to?

Sub Process_Globals
 Private fx As JFX
 Private MainForm As Form
 Private TabPane1 As TabPane
 
 Private Button1 As Button
 Private Button2 As Button
 Private Button3 As Button
 Private Pane1 As Pane
 Private Pane2 As Pane
 Private Shown1,Shown2,Shown3 As Boolean  ' <<<<<<<<<<<<<<< new bit
End Sub
Sub AppStart (Form1 As Form, Args() As String)
 MainForm = Form1
 MainForm.RootPane.LoadLayout("1")
 MainForm.Show
 MainForm.Stylesheets.Add(File.GetUri(File.DirAssets, "TabPane.css"))
 TabPane1.LoadLayout("2", "Tab 1")
 Shown1=True
End Sub
Sub Button1_Click  'forward to Tab 2
 If Shown2=False Then
  TabPane1.LoadLayout("3", "Tab 2")
  Shown2=True
 End If
 TabPane1.SelectedIndex = 1
End Sub
Sub Button2_Click  'back to previous
 If Shown1=False Then 
  TabPane1.LoadLayout("2", "Tab 1")
  Shown1=True
 End If
 TabPane1.SelectedIndex = TabPane1.SelectedIndex - 1
End Sub
Sub Button3_Click  'forward to Tab 3
 If Shown3=False Then
  TabPane1.LoadLayout("3", "Tab 3")
  Shown3=True
 End If
 TabPane1.SelectedIndex = 2
End Sub