This project explorer can be opened/closed using the
View -> Project explorer
menu or via the "Show project explorer" icon in the file toolbar.
It gives an overview of the structure of a project and allows the user to perform various operations on the
windows (tables and plots) in the workspace: hiding, minimazing, closing, renaming, printing, etc...
These functions can be reached via the context menu, by right-clicking on an item in the explorer.
By double-clicking on an item, the corresponding window is shown maximized in the workspace,
even if it was hidden before.