Error Highlighting in NetBeans Editor

[Judi Rastall]

I am pulling my hair out on this one. I am using Apache NetBeans IDE 
12.3 and have always loved it ... until recently. It always used to 
highlight warnings in my code with yellow underlining and errors with 
red underlining and there would be little coloured ticks down the 
right-hand margin alongside each highlighted line. I found this so very 
useful when chasing down errors and omissions.

A week or back this disappeared and I am lost without it. I am guessing 
I hit a key-combination to switch it off but I cannot find how to switch 
it back on again. Can anyone help me with how to switch this facility 
back on, please?

Judi R