As a long time Dolphiner is not much time that I'm using IdeaSpace and let me comment that is a really handy and useful tool.
Basically IdeaSpace allows to group in a single window every Dolphin window that you are using in a development session, with exception of the Transcript.
Each window that is added to an IdeaSpace window have its own tab to make easy and homy to switch between one or more class browser's, view composer's, workspaces, package manager, etc.
A sample of one of my current projects, next:
