Description:           

We can change the back color and fore color of rich textbox by selected color from color dialog, Change the Text font size, type by the font dialog.

Color Dialog

>private Sub showcolor()

For i = 0 To 1

                    ColorDialog1.ShowDialog()

                    If i = 0 Then

                        If ColorDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then

                            RichTextBox1.BackColor = ColorDialog1.Color

                        End If

                    End If

                    If i = 1 Then

                        If ColorDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then

                            RichTextBox1.ForeColor = ColorDialog1.Color

                        End If

                    End If

                Next

End Sub