Как быстро работать с комбинациями стилей текста(жирный, курсив, жирный + курсив и т. д.) в Visual Basic?

Public Class Form1
    Dim U As Boolean
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        If U = True Then
            RichTextBox1.Font = New Font(RichTextBox1.SelectionFont.FontFamily, RichTextBox1.SelectionFont.Size, FontStyle.Bold Or FontStyle.Italic Or FontStyle.Underline)
        Else
            RichTextBox1.Font = New Font(RichTextBox1.SelectionFont.FontFamily, RichTextBox1.SelectionFont.Size, FontStyle.Regular)
            U = False
        End If
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        RichTextBox1.Text = "раз дра три"
    End Sub
End Class

    Private Sub Form6_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.LoadFontFamily()
        Me.LoadFontSize()
    End Sub
 
    Private Sub ComboBox_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged, ComboBox2.SelectedIndexChanged
        Me.SetFont(Me.ComboBox1.SelectedText, Me.ComboBox2.SelectedItem)
    End Sub
 
    Private Sub CheckBox_CheckedChanged([sender] As Object, [ea] As EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged, CheckBox3.CheckedChanged
        Me.SetFont(Me.ComboBox1.SelectedText, Me.ComboBox2.SelectedItem)
    End Sub
 
    Private Sub SetFont([family] As String, [size] As Integer, [style] As System.Drawing.FontStyle)
        Me.RichTextBox1.Font = New Font(family, CSng(size), style)
    End Sub
 
    Private Sub LoadFontFamily()
        For Each oneFontFamily As System.Drawing.FontFamily In System.Drawing.FontFamily.Families
            Me.ComboBox1.Items.Add(oneFontFamily.Name)
        Next
        Me.ComboBox1.SelectedText = "Arial"
    End Sub
 
    Private Sub LoadFontSize()
        For i As Integer = 6 To 60 Step 1
            Me.ComboBox2.Items.Add(i)
        Next
        Me.ComboBox2.SelectedItem = 14
    End Sub
 
    Private Function GetStyle() As System.Drawing.FontStyle
        If sender Is Nothing Then Exit Function
        Dim tmpStyle As Integer = 0
 
        If CheckBox1.Checked Then
            tmpStyle += 1
        End If
 
        If CheckBox2.Checked Then
            tmpStyle += 2
        End If
 
        If CheckBox3.Checked Then
            tmpStyle += 4
        End If
        Return tmpStyle
    End Function