I have implemented a docking tray system in several interface designs to great affect. In designs where widgets and tools need to be accessed quickly and frequently, the shelves allow users to open only the trays they need. Common shelves will include Navigation, Tools, Fileters, and Data. This shelves can also be contextual depending on the current function or selection. The applications I have used these for have been dashboards and mapping interfaces where a maximum content area is appreciated. Additional viewing area or scale is increased when docs are collapsed.