When a workspace is used (either created new or opened) it is added to a list called recent workspaces: this list maintains the unique list of used files, in order of date of use (from most recent) with the purpose of being able to quickly reopen them in the workspace.
Select the Workspace/Recents submenu then the desired workspace in the list: as soon as it is selected, you will be prompted to open it immediately.
NOTE: The recent workspace list is unique to the individual RDE installation.
Workspace History
The sub-menu can display up to a maximum of 10 workspaces: in case the recent workspace list contains more than 10 workspaces, the Historical workspace. command is activated in the sub-menu itself, which provides access to a window containing the complete list of recent workspaces.
In the window, select the desired workspace, then press Open (or hotkey Enter or double-click on the workspace itself) to open the workspace, or press Cancel (or hotkey Esc) to cancel the current operation.