Now, whenever you want to make use of one the minimized windows, just hover over it in the sidebar where you minimized it. Immediately, the window pops up and you can use it again. As shown in the illustration above, you can remove a window from the sidebar by deselecting the Minimize Window popup menu item. This means that your resources are much more quickly available to you than they are when you access everything via menus and shortcut keys -- and you can see what's available to you, because everything's neatly docked in visible sidebars.
(To find out how to do this in your own NetBeans plug-ins, see the draft version of the NetBeans Anagram Game Plug-in Tutorial. Note that this tutorial is incomplete, currently, because serialization isn't discussed yet so that, when you close the IDE, the position of the windows isn't saved.)
If you like belated flashes of understanding such as this one, here are some more: