This page of the Impact Explorer toolbox can be used to navigate through the layer and block structure of the drawings that you have open as well as switching instantly between open projects.
Impact Explorer - Drawings Hierarchy
The Drawings Hierarchy page consists of two panels; the Drawings Hierarchy and the Block Inspector.
TIP: If the Block Inspector is not visible, right-click on the Drawings Hierarchy and use Show Block Inspector from the context menu.
The Drawings Hierarchy shows the open projects and their layers. The current project is shown bold, while the current layer is highlighted. The Block Inspector shows all the blocks, symbols and layers that are inserted within the current layer.