One and two panels...

[KLASS]

From the help (context menu):

Custom Context Menu Commands (List)
...
...
Copy/Move to Other Pane
The commands Panes | Move to Other Pane and Panes | Copy to Other Pane are show if Dual Pane is enabled.

Perhaps these menu items should be hidden, too, if one panel:

[Horst]

May be you should have posted this into the Wishes sub-forum.
I don't see here an error or anything bad happen.

[KLASS]

May be you should have posted this into the Wishes sub-forum.
I don't see here an error or anything bad happen.

You're probably right, but "the train has already left the station.
I'll make it up to you another time.

[PeterH]

To be in single pane mode isn't enough reason to hide these entries.
As the other pane does exist - it's only hidden. And often I wish to copy to that pane!

So you must hide them explicitely!

[eil]

IMO those menu items have no reason to be hidden, 'cause as PeterH said second panel is just hidden and it's normal to have dual panel corresponding items always active.(I actually wonder Why visiting Dual panel menu at all, if user works in one panel mode and shouldn't care about that menu)