Top ListView in SplitContainer won't add vertical scrollbar - winforms

Question

I have a Winforms app with two ListViews in a SplitContainer.
When I drag the splitter to hide part of the Panel2 ListView items, it automatically adds a vertical scrollbar.
When I drag the splitter to hide part of the Panel1 ListView items, it does not add a vertical scrollbar.
Changing which ListView is in which Panel has the same behavior. It's as if something about the SplitContainer or its panels is controlling whether the vertical scrollbar is added to the ListView in Panel1 or not. How to make whichever ListView is in the top Panel1 also automatically add the vertical scrollbar?
To replicate, create a simple Winforms application with one form. Here is my form code followed by the designer form code.
Public Class Form1
Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown
Timer1.Enabled = True
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Try
Timer1.Enabled = False
TechDateList.BeginUpdate()
TechDateList.Items.Clear()
StopsList.BeginUpdate()
StopsList.Items.Clear()
For i As Integer = 1 To 5
Dim techItem = New ListViewItem
techItem.UseItemStyleForSubItems = False
techItem.SubItems(0).Text = Date.Now.ToString("MMM dd, yyyy")
techItem.SubItems.Add(String.Format("Tech {0}", i))
TechDateList.Items.Add(techItem)
Next
For i As Integer = 1 To 5
Dim stopItem = New ListViewItem
stopItem.UseItemStyleForSubItems = False
stopItem.SubItems(0).Text = Choose(i, "AAA", "BBB", "CCC", "DDD", "EEE")
stopItem.SubItems.Add(String.Format("Stop {0}", i))
StopsList.Items.Add(stopItem)
Next
Catch ex As Exception
MsgBox(ex.ToString(), MsgBoxStyle.Critical + MsgBoxStyle.OkOnly, "Timer1_Tick Error 1")
Finally
TechDateList.EndUpdate()
StopsList.EndUpdate()
End Try
Try
ListSplitter.Panel1Collapsed = False
ListSplitter.SplitterDistance = 125
ListSplitter.SplitterWidth = 6
TechDateList.Items.Item(0).Selected = True
Catch ex As Exception
MsgBox(ex.ToString(), MsgBoxStyle.Critical + MsgBoxStyle.OkOnly, "Timer1_Tick Error 2")
End Try
End Sub
End Class
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class Form1
Inherits System.Windows.Forms.Form
'Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
Try
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
Finally
MyBase.Dispose(disposing)
End Try
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.components = New System.ComponentModel.Container()
Me.ListSplitter = New System.Windows.Forms.SplitContainer()
Me.TechDateList = New System.Windows.Forms.ListView()
Me.UInitial = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.SchedDate = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.StopsList = New System.Windows.Forms.ListView()
Me.StopNum = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.StopName = CType(New System.Windows.Forms.ColumnHeader(), System.Windows.Forms.ColumnHeader)
Me.Timer1 = New System.Windows.Forms.Timer(Me.components)
CType(Me.ListSplitter, System.ComponentModel.ISupportInitialize).BeginInit()
Me.ListSplitter.Panel1.SuspendLayout()
Me.ListSplitter.Panel2.SuspendLayout()
Me.ListSplitter.SuspendLayout()
Me.SuspendLayout()
'
'ListSplitter
'
Me.ListSplitter.Dock = System.Windows.Forms.DockStyle.Fill
Me.ListSplitter.FixedPanel = System.Windows.Forms.FixedPanel.Panel1
Me.ListSplitter.Location = New System.Drawing.Point(0, 0)
Me.ListSplitter.Name = "ListSplitter"
Me.ListSplitter.Orientation = System.Windows.Forms.Orientation.Horizontal
'
'ListSplitter.Panel1
'
Me.ListSplitter.Panel1.Controls.Add(Me.TechDateList)
Me.ListSplitter.Panel1Collapsed = True
Me.ListSplitter.Panel1MinSize = 0
'
'ListSplitter.Panel2
'
Me.ListSplitter.Panel2.Controls.Add(Me.StopsList)
Me.ListSplitter.Size = New System.Drawing.Size(384, 261)
Me.ListSplitter.SplitterDistance = 25
Me.ListSplitter.SplitterWidth = 1
Me.ListSplitter.TabIndex = 1
'
'TechDateList
'
Me.TechDateList.Anchor = CType(((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _
Or System.Windows.Forms.AnchorStyles.Left), System.Windows.Forms.AnchorStyles)
Me.TechDateList.Columns.AddRange(New System.Windows.Forms.ColumnHeader() {Me.UInitial, Me.SchedDate})
Me.TechDateList.FullRowSelect = True
Me.TechDateList.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.None
Me.TechDateList.HideSelection = False
Me.TechDateList.LabelWrap = False
Me.TechDateList.Location = New System.Drawing.Point(4, 0)
Me.TechDateList.Margin = New System.Windows.Forms.Padding(0)
Me.TechDateList.MultiSelect = False
Me.TechDateList.Name = "TechDateList"
Me.TechDateList.ShowGroups = False
Me.TechDateList.Size = New System.Drawing.Size(258, 166)
Me.TechDateList.TabIndex = 0
Me.TechDateList.UseCompatibleStateImageBehavior = False
Me.TechDateList.View = System.Windows.Forms.View.Details
'
'UInitial
'
Me.UInitial.Text = "Route"
Me.UInitial.TextAlign = System.Windows.Forms.HorizontalAlignment.Center
Me.UInitial.Width = 100
'
'SchedDate
'
Me.SchedDate.Text = "Job Date"
Me.SchedDate.Width = 133
'
'StopsList
'
Me.StopsList.Anchor = CType(((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _
Or System.Windows.Forms.AnchorStyles.Left), System.Windows.Forms.AnchorStyles)
Me.StopsList.Columns.AddRange(New System.Windows.Forms.ColumnHeader() {Me.StopNum, Me.StopName})
Me.StopsList.FullRowSelect = True
Me.StopsList.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.None
Me.StopsList.HideSelection = False
Me.StopsList.LabelWrap = False
Me.StopsList.Location = New System.Drawing.Point(4, 0)
Me.StopsList.Margin = New System.Windows.Forms.Padding(0)
Me.StopsList.MultiSelect = False
Me.StopsList.Name = "StopsList"
Me.StopsList.ShowGroups = False
Me.StopsList.Size = New System.Drawing.Size(258, 252)
Me.StopsList.TabIndex = 0
Me.StopsList.UseCompatibleStateImageBehavior = False
Me.StopsList.View = System.Windows.Forms.View.Details
'
'StopNum
'
Me.StopNum.Text = "000"
Me.StopNum.TextAlign = System.Windows.Forms.HorizontalAlignment.Center
Me.StopNum.Width = 34
'
'StopName
'
Me.StopName.Text = "Stop Name"
Me.StopName.Width = 199
'
'Timer1
'
Me.Timer1.Interval = 250
'
'Form1
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(384, 261)
Me.Controls.Add(Me.ListSplitter)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ListSplitter.Panel1.ResumeLayout(False)
Me.ListSplitter.Panel2.ResumeLayout(False)
CType(Me.ListSplitter, System.ComponentModel.ISupportInitialize).EndInit()
Me.ListSplitter.ResumeLayout(False)
Me.ResumeLayout(False)
End Sub
Friend WithEvents ListSplitter As SplitContainer
Friend WithEvents TechDateList As ListView
Friend WithEvents UInitial As ColumnHeader
Friend WithEvents SchedDate As ColumnHeader
Friend WithEvents StopsList As ListView
Friend WithEvents StopNum As ColumnHeader
Friend WithEvents StopName As ColumnHeader
Friend WithEvents Timer1 As Timer
End Class

Answer 1

From what I see in Designer code, TechDateList Height exceeds ListSplitter.Panel1 Height:
Me.ListSplitter.SplitterDistance = 25
Me.TechDateList.Size = New System.Drawing.Size(258, 166)
make sure that TechDateList fits Panel1 in Designer, e.g
Me.ListSplitter.SplitterDistance = 125
Me.TechDateList.Size = New System.Drawing.Size(258, 120)
and then resize will work as expected.
consider also docking TechDateList to Left - the list will get maximum possible Height and will resize with Panel1

Answer 2

I'm guessing that moving the splitter is resizing the ListView in Panel2 but not resizing the ListView in Panel1. I'm probably missing something simple somewhere. Regardless, if I add this code to the form, I get the desired results:
Private Sub ListSplitter_SplitterMoved(sender As Object, e As SplitterEventArgs) Handles ListSplitter.SplitterMoved
TechDateList.Height = ListSplitter.Panel1.Height
End Sub