Just try again your exercise but this time change format to csv and then change back to delimited.
After that checkbox Header does not longer works.... at least in my 188.8.131.521
yeah, i see what you mean now - that would be a bug.
Sorry for having to say so - if you want to log bugs, please use My Oracle Support.
Are you saying that any error or malfuction pointed out here won't be logged as a bug?
Correct - the forum is NOT for reporting bugs. It is for helping people with problems/issues using Sql Developer.
There is no work-around for your problem so no further help is possible.