To select multiple items in the 
Guests, 
Groups or 
Schematic pane:
| • | To select multiple individual items Ctrl+click on each item. |
| • | To select a group of items click on the first item and Shift+click on the last item. |
| • | To select multiple groups of items Ctrl+click on the first item in each group and Shift+Ctrl+click |
To select multiple items in the 
Floor Plan pane:
| • | Ctrl+click on each item. |
To select all visible items in any of the above panes use Edit>Select All or Ctrl+A.