Powerbuilder 7 crash when data window size is smaller than actual data in DB

I've just started Powerbuilder and came to know this community. Could you advise how to avoid below problem?

In Powerbuilder 7 with Oracle Client 11g, it crashes in case data window column size(eg. Char 50)
is different from DB column size(eg. varchar 200), i.e. data window size is smaller than actual data size. We can't upgrade PB right now. How about substring function ? If it makes sense, can I have some sample code ? Many thanks!