Slider panel that hides components inside it - vb.net

Question

What event(s) would I use to handle hiding a button/component that is inside this panel? This is a sliding panel that when the user hovers over, it expands and when the mouse exits, it collapses.
The problem is I don't know how to keep the components from showing until it is expanded.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Panel1.Dock = DockStyle.Left
Timer3.Enabled = True
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
If Panel1.Width < 150 Then
Panel1.Width = Panel1.Width + 100
ElseIf Panel1.Width = 150 Then
Timer1.Enabled = False
End If
End Sub
Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
If Panel1.Width >= 100 Then
Panel1.Width = Panel1.Width - 50
If Panel1.Width < 100 And Panel1.Width > 25 Then
Panel1.Width = Panel1.Width - 1
End If
ElseIf Panel1.Width = 25 Then
Timer2.Enabled = False
End If
End Sub
Private Sub Timer3_Tick(sender As Object, e As EventArgs) Handles Timer3.Tick
If Panel1.ClientRectangle.Contains(Panel1.PointToClient(MousePosition)) Then
If Not Timer1.Enabled AndAlso Panel1.Width < 150 Then
Timer1.Enabled = True
Timer2.Enabled = False
End If
Else
If Not Timer2.Enabled AndAlso Panel1.Width > 25 Then
Timer1.Enabled = False
Timer2.Enabled = True
End If
End If
End Sub
End Class

Answer 1

You should probably rename your timers to keep them straight, something like SlideOpenTimer and SlideCloseTimer, etc. Would make it easier to understand what the timers are for.
I re-worked your timer events to hide the ListBox when the closing timer starts and to show the ListBox when the panel reaches its full width:
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
If Panel1.Width < 100 Then
Panel1.Width += 50
ElseIf Panel1.Width < 150 Then
Panel1.Width += 25
ElseIf Panel1.Width >= 150 Then
Timer1.Enabled = False
ListBox1.Visible = True
End If
End Sub
Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
If ListBox1.Visible Then
ListBox1.Visible = False
End If
If Panel1.Width > 100 Then
Panel1.Width -= 50
ElseIf Panel1.Width > 25 Then
Panel1.Width -= 25
ElseIf Panel1.Width <= 25 Then
Timer2.Enabled = False
End If
End Sub