Israel,

This seems to be a limitation of the .NET TextBox.  When the UltraTextEditor goes into edit mode, it positions a TextBox within its bounds for editing, which is why you see the change in behavior when the control gets focus.  I tested this with a standalone TextBox and it started to wrap its text after 1024 characters as well.  The UltraTextEditor, when not in edit mode and set to not wrap its text, does not have this limitation.

-Matt

There is no limit that I am aware of on the number of text items per line.  I'm assuming that you have Multiline set to True, in which case you might consider setting WordWrap to False.

-Matt

When are you trying to execute this code?  You would likely need to do this in a CreationFilter because the elements could be repositioned several times throughout the course of the application, and doing this in AfterCreateChildElements will ensure that you actually do have elements to work with.

-Matt

It's hard to tell what would have change to cause an error based only on this code.  My guess it it might have something to do with the AutoComplete logic that is tied to the combo editors, but I can't really say for certain.  If you can attach a small sample project to this post, I'll be happy to look into it.  You could also submit an incident to Developer Support.

-Matt

Can you provide any additional information about how your UltraComboEditor is setup, which properties are set, etc?  It seems like, from the stack trace, the AutoCompleteMode property is set, but I can't seem to reproduce this problem.  It would be much easier if you could post a small sample demonstrating the problem, since I can't seem to reproduce the issue on my machine despite attempting various combinations of AutoCompleteMode, LimitToList, and attempting to set the Text or Value via a button click so that the editor isn't in edit mode.

-Matt

You might be better off trying to do this in the AfterEnterEditMode event, since at that point you don't have to worry about timing issues with the cell going into edit mode.

-Matt

The UltraTextEditor uses a .NET TextBox when in edit mode; do you have the same problem when using a TextBox?  It's possible that you need to convert the carriage return to the Environment.Newline character, or whatever character the TextBox recognizes (which I think is "\r\n").

-Matt