' Set the specified font size to the selection of a RichTextBox' Example: SetFontSize(richTextBox1, 16)Public Sub SetFontSize(ByVal rtb As RichTextBox, ByVal fontSize As Single)    ' if the selection length is > 0, work char by char    If rtb.SelectionLength > 0 Then        Dim selStart As Integer = rtb.SelectionStart        Dim selLength As Integer = rtb.SelectionLength        Dim currFont As System.Drawing.Font        Dim i As Integer        For i = 0 To selLength - 1            ' select 1 char            rtb.Select(selStart + i, 1)            ' get the current font            currFont = rtb.SelectionFont            ' create and assign to the char a new font             ' with the new style            rtb.SelectionFont = New Font(currFont.FontFamily, fontSize, _                currFont.Style)        Next        ' reselect the original selection        rtb.Select(selStart, selLength)    Else        rtb.SelectionFont = New Font(rtb.SelectionFont.Name, fontSize, _            rtb.SelectionFont.Style)    End IfEnd Sub