Why does TextBox replace all new lines with CR line feeds?

[aquinn39]

I've noticed that whenever text is added to a TextBox (i.e. setting the Text property), all of the new lines are replaced with CR (\r) line feeds. This can cause problems as various applications don't recognise these as new lines but do recognise CRLF (\r\n), such as batch files for example. As far as I know, the default for Windows is usually CRLF, so why does the TextBox use CR (which is used by MacOS)? Why not use CRLF or just keep the new lines as they were?

I was wondering if anyone knows anything about this behaviour? I can't find a huge amount of info on this other than this issue report and this. But there's no solutions or even confirmation that this is a bug or intentional behaviour. It seems like this used to work properly but was broken in a Windows 10 feature update.

[codendone]

In short, this behavior is because TextBox internally uses RichEdit to implement all of the complex textbox behavior, and the default behavior of RichEdit is to use just CR at line breaks. You can find some comments on that here: about rich edit controls

RichEdit can be asked to convert for CRLF or LF for some APIs, but I believe internally it always stores as just CR. I think LF would probably be the best choice if this was a new control, but the default can't be changed now without a huge compatibility break.

For those conversion scenarios, when using RichEditBox (which more directly exposes the RichEdit functionality), you can call ITextRange.GetText with TextGetOptions.UseCrlf or TextGetOptions.UseLf to have it convert the returned string to the desired form. See TextGetOptions docs for more info, which also shows that the UseLf option was apparently added in 2017. ITextRange.SetText has similar options to support converting the text you're setting. But, of course, none of this helps for TextBox, which doesn't expose any options.