Getting started...

Hi everyone,

I'm a complete beginner getting started with my first plugin development.. more specifically a GUI designer similar to JFormDesigner (but simpler). I've looked at some of the articles on this page http://confluence.jetbrains.com/display/IDEADEV/PluginDevelopment

So far looking at the demos I can only see the addition of menu commands or an icon or something like that.. for example as described in this page
http://www.jetbrains.com/idea/plugins/action_system.html
I have no idea how to even start researching on how to produce something like the one shown in the intellij plugin screenshot shown here: http://www.formdev.com/jformdesigner/screenshots/
(or you can find it attached)

I have a working simple stand-alone GUI designer application and just looking to port to a plugin. But just need a push in the right direction.. specifically which articles would be most useful, and are there any open-source plugins that might help me develop the skills needed. It would be nice to understand how the designers of JFormDesigner managed to make such a layout for the plugin like the one in the screenshot. Obviously my expectations are not too high at the moment, just getting a really really simple example plugin running would be nice.

I realize this is quite an open question (hopefully I'm not breaking any rules for question asking). Thank you in advance. (and happy new year :p)