The "Edit" drop down menu contains the following options:
Undo Ctrl+Z
Redo Ctrl+Shift+Z
Cut Ctrl+X
Copy Ctrl+C
Paste Ctrl+V
Delete Ctrl+Shift+X
Duplicate Ctrl+2
Select Parent
Select All Ctrl+A
Deselect All Ctrl+Shift+A
Group Ctrl+G
Ungroup Ctrl+Shift+G
Hide > Selected Ctrl+J
Unselected Ctrl+H
Show Ctrl+Shift+H
Show Clipboard
These are generic operations performed on objects in the Ez3d scene. Most of the operations work on the currently selected object(s). To select an object, just click on it in any of the viewers, or select using "Scene - Object List". To select another object instead of the first, just click on the second object. But if you want to select the second object in addition to the first, click on it while keeping <Shift> pressed. To deselect all objects, click on an empty part of the scene, or choose "Edit - Deselect All".
When an object is selected, by default, a 3D manipulator appears around it. You can use the manipulator to move and scale the object (see "Attribute - Transform"). You can also set the selection highlight to other forms by using "Options - Selection Highlight".
