substring () to cut string?

First of all, you should understand that you never "cut" a string. Strings are immutable. Once initialized, they cannot be modified at all. When you use System.Substring on some variable, you actually create a brand-new string with appropriate constant and assign the reference to the newly created string. If you assign it to the same variable, its referential identity is always lost, as the reference is replaced with the second reference reference created when the first one was still in use. Is that clear?

Now, I have no idea why do you have a problem with "shattering the frame", because you did not tell us what kind of UI you are using. So please, deal with it by yourself or ask another question. It has nothing to do with "cutting" the string at all. Whatever the UI is, the summary tends to occupy different space, depending on string length, those line separators and other factors. You will need to solve this problem anyway.

As to the summary, I will strongly advice you to change the data model a bit. Here is why: I looks like you idea is to use abbreviated detailed description as a summary. I think this is a bad idea. Such abbreviated strings rarely make adequate summary. Therefore, you should keep description and summary as two different entities. And your user, despite the need of entering separate text for summary, would be more happy. It looks like you wanted to make summary "automatically". It would limit the user's freedom; most users will hardly like that.

—SA