Steps to reproduce:

1. Create web scenario
2. Try adding any hardcoded variable with length 255+ chars or one with regex, for example "regex:.*" (just select whole page for purpose of test) 

Result:
Can't manually enter variables larger that 255 chars.
Regex match is trimmed after 255 chars.
Expected:
It's expected that you can't add variable with 255+ chars, because fields has limits for it. But it's not expected that regex match will be trimmed to 255 chars. Would expect variable to contain whole match even if it's larger that 255 chars. 

It would really help if variables could be larger that 255 fields. We use web scenarios to check some forms that have input values larger that 255 and regex is able to get correct value, but it's trimmed anyways. As I understand variables are not stored in any long-term storage and are dumped after request ends, so I hope it's possible to increase max field length.