Underlines

[Leon Pollak]

Hello.

I am not sure when it began, but...
Looking at the text of the project I see that many identifiers are underlined. 
Part of them by bright yellow line, while another part - by dark grey line.
I was not able to understand what this underlining means - although most of 
them were under global variables, but there are also under constants and 
sometimes under "normal" variables.
How can I remove these underlines (very annoying...)

Thanks a lot.
-- 
Leon