NetBeans. Disable error checking underline

Question

How to disable error checking in NetBeans 6.9.1? It is very annoying to have red line in the source code.

This is similar to NetBeans - Turn off - wavy red underlines -

Answer 1

I would just click on the hint on the left side by the line numbers, it should create a pop-up, while that's still up click on the hint again. Now another pop-up will be there asking if you want to turn off the error check for either that single file, or for all files. Choose for that file, b/c it should be off by default.