I started to play arround with windowbuilder and I have already built a few basic GUI programs. However, I was wondering if I'm doing myself a disservice by learning swing this way instead of building everything myself, without using any plugins? I do have a good understanding of what goes into building the whole GUI, but still, what's your opinion on the matter?
I usually give the same example. You can't teach someone to use a calculator before teaching him how to sum. I think it's important for you to get familiarized with most of the swing components and try to grasp the basics about them so you can code them easily.
WindowBuilder is very helpful for complex designs and components, but I think you should first know the fundamentals before switching to WindowBuilder. Many people would disagree with me because that extension makes life a lot easier but it's really important to know the basics in case someday you want to work somewhere without WindowBuilder or NetBeans, or even if you want to understand the code that the program is making for you.
So, to sum up: You can install WindowBuilder and use it to learn but keep in mind you may not get some VERY useful knowledge with this method. Also, analyze the code thoroughly to understand it and try not to over-use the tool.