BUG: ComboBox does not clear when you set SelectedIndex to -1

• Method 1
  Use the following code to assign the value -1 to the SelectedIndex two times in a row:

  ComboBox1.SelectedIndex = -1
  ComboBox1.SelectedIndex = -1
  					

• Method 2
  Use the following code to assign the value 0 to the SelectedIndex first, followed by the value -1:

  ComboBox1.SelectedIndex = 0
  ComboBox1.SelectedIndex = -1
  					

• Method 3
  Use the following code to add the items to the control manually instead of binding to a datasource:

     Dim DataTbl As New DataTable("DemoTable")
     Dim DataCol1 As New DataColumn()
     Dim DataCol2 As New DataColumn()
     Dim DRow As DataRow
     Dim counter As Int32
  
     DataCol1.DataType = GetType(Int32)
     DataCol1.ColumnName = "ID"
     DataCol1.AutoIncrement = True
     DataTbl.Columns.Add(DataCol1)
     
     Dim Key(0) As DataColumn
     Key(0) = DataCol1
     DataTbl.PrimaryKey = Key
  
     DataCol2.DataType = GetType(String)
     DataCol2.ColumnName = "CompanyName"
     DataTbl.Columns.Add(DataCol2)
  
     For counter = 0 To 10
        DRow = DataTbl.NewRow()
        DRow("CompanyName") = "John " & counter.ToString
        DataTbl.Rows.Add(DRow)
     Next
  
     ' Populate the ComboBox manually
     Dim dr As DataRow
     For Each dr In DataTbl.Rows
        ComboBox1.Items.Add(dr("CompanyName"))
     Next
  					

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Steps to reproduce the behavior

1. Create a new Windows Application.
2. Add a ComboBox and a Button control to the form.
3. Double-click the form and then enter the following code on the Load event of the form:

      Dim DataTbl As New DataTable("DemoTable")
      Dim DataCol1 As New DataColumn()
      Dim DataCol2 As New DataColumn()
      Dim DRow As DataRow
      Dim counter As Int32
   
      DataCol1.DataType = GetType(Int32)
      DataCol1.ColumnName = "ID"
      DataCol1.AutoIncrement = True
      DataTbl.Columns.Add(DataCol1)
      
      Dim Key(0) As DataColumn
      Key(0) = DataCol1
      DataTbl.PrimaryKey = Key
   
      DataCol2.DataType = GetType(String)
      DataCol2.ColumnName = "Name"
      DataTbl.Columns.Add(DataCol2)
   
      For counter = 0 To 10
         DRow = DataTbl.NewRow()
         DRow("Name") = "John " & counter.ToString
         DataTbl.Rows.Add(DRow)
      Next
   
      With ComboBox1
         .DataSource = DataTbl 
         .ValueMember = "ID"
         .DisplayMember = "Name"
      End With
   					

4. Double-click the Button to insert code for the Click event:

   ComboBox1.SelectedIndex = -1
   					

5. Press F5 to run the application.
6. Select an item, other than the first one, from the ComboBox and then press the Button on the form.
   
   The first item now appears in the ComboBox. If you press the Button a second time, the ComboBox clears.

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