Although you can have only one workspace open at a time, you can add as many targets to the workspace as you want and open and edit objects in multiple targets.
To add an existing target to a workspace:
Right-click on the workspace displayed in the System Tree and select Add Target from the pop-up menu.
The Add Target to Workspace dialog box displays.
Navigate to the directory containing the target you want to add and select the target (.pbt) file.
Click Open.
The target is added to your current workspace.
