Changing where perspectives open
  You can change the default behavior for how perspectives are opened in the Workbench.
  
    - Open the 
    
 General > Perspectives
    preference page. 
    - Select either In the same window or In a new window from the Open a new perspective
    group.
 
    - Click OK.
 
  
  Perspectives
  Opening perspectives
  Specifying the default perspective
  Switching between perspectives
  Showing and hiding menu items and toolbar buttons
  Configuring perspective command groups
  Configuring perspective shortcuts