Actually, you don't even have to do all that. I just did a quick test and was able to do it:



It was as simple as first declaring a class variable as a List(Of String). You can declare the variable anywhere though.

Then in the CheckBox's CheckChanged event, I looped through each .Line in the TextBox and called .Add on my List(Of String).

Then I looped through each string in the List and added it to the TextBox via:

VB.NET Code:
  1. Me.txtTest2.Text &= Me.txtChar.Text & s & Me.txtChar.Text & Environment.NewLine

If you look through my post carefully, I've given you everything you need to know.