Tree Popup Menu
This window appears on right-clicking on an object in the tree view, in
either the constants or the overlays window.
Rename
Rename Object.
Copy
Copy object and children to clipboard.
Copy With Linked Items
Copy selected node and items linked to it (i.e. items lower down in
the hierachy).
Paste
Insert object from clipboard here.
Delete
Delete selected object.
Move Up
Move selected object up one place in the tree view.
Move Down
Move selected object down one place in the tree view.
Invert
Invert current spectrum.