I'm currently employed by a business to do website development in Wordpress. I've written a number of custom plugins specifically for a number of clients over the time of my employment.
Today, I asked my boss what I would be allowed to use as code samples because I'm quitting. My boss has forbidden me from taking any of the custom plugins I coded (which is all of the programming work I've done). However, all of those custom plugins I coded are currently licensed under the the GPL (though they were never released or shared).
If I was to take this custom code that I wrote under the GPL (but never released) and provide it as code samples anyway, would my current employer be able to take any kind of legal action against me?