Visual Studio like Adjustable Layout for Web Design [on hold]

Are there any tools which allow you to design a user interface which the user can configure? In other words, so the user can arrange where the windows (blocks/frames) are positional within the webpage?

Initially, I was hoping to find a layout tool similar to the layout features which are found in Visual Studio. At this point though, I would just be happy to find documentation related to the concept of a user configurable layout. I can hardly find any documentation related to the subject; I might not be searching with the correct string ... the correct terminology for 'user configurable layout'.

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EDIT: I was able to find some good information and also good javascript demos when searching 'Dockable windows in javascript'