In the dockable panel you can see all your currently open views. They are grouped by their parent file, which groups can be collapsed. The views are sorted by their type and by their name. Their type is shown by the little icon on the left, and also in the tooltip, above their view template if there is any. Your active view is shown in bold. Your views will be automatically added once opened.
Furthermore the actual count of open views will be shown in the group header on the right in the following format: file / total.
Quite straightforward, just double-click on any.
Clicking on any group header will collapse or expand it's content accordingly.
Middle mouse button clicks will close any open views, or complete projects. It can be used to remove any recent views too.
Using the right mouse button you can get the context menu which has the following functions:
Closes the highlighted view