Private Sub btnConvert_Click(sender As Object, e As EventArgs) Handles btnConvert.Click

    Dim dValueOfTxtBoxFrom As Double = 0

    If Me.cboFrom.SelectedIndex = -1 AndAlso Me.cboTo.SelectedIndex = -1 Then
      MessageBox.Show("Please select temperature units to convert from and to.", "Error: 10001", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
      'btnReset.Select() 'works fine

    ElseIf cboFrom.SelectedIndex = -1 OrElse cboTo.SelectedIndex = -1 Then
      MessageBox.Show("Please select temperature units to convert from and to.", "Error: 10001", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
      'btnExit.Select() 'works fine

    End If