Most scanners scans expressions like -1 mistakenly as operator(-)integer(1) where it should be returning integer(-1). It's not easy to avoid expressions like i-1 getting highlighted as ident(i)operator(+)integer(1), but it's possible (see Ruby scanner).

I removed the recognition of -1 tokens in r255. This is only a hotfix; to really fix it, we need to keep track of some value_expected state. The Ruby Scanner can do this, and the Scanners for Java, C, Delphi, and Python will need it, too.

From Redmine: http://odd-eyed-code.org/issues/47