If only one item is selected, the pane-interface-copy-object method for choice returns what
item-pane-interface-copy-object returns for this item. In this case all three of the return values are used.
If multiple items are selected, pane-interface-copy-object applies
item-pane-interface-copy-object to each one, and returns a list of the returned objects as the first value, and a concatenation of returned strings (separated by newlines) as the second value. The plist is ignored if the there more than one element.
The default method returns the item and its print representation (using the print-function of the choice), and no third return value.
You can define your own methods for
item-pane-interface-copy-object. This is useful to make active-pane-copy work properly for a choice, in cases where the actual items in the choice are not the objects that are displayed in the choice as far as the user is concerned. For example, you may have a structure
To give different colors to different lines in a list-panel. In this case pane-interface-copy-object (and hence active-pane-copy when the list-panel is active) will return the
my-item structure, while the user will expect the real object. This can be fixed by adding a method:
CAPI User Guide and Reference Manual (Windows version) - 3 Aug 2017