Well, we do call it a context menu.
But yes, there is no explicit context to commands as nothing is selected to give them context.
I have already reported this. I previously logged this as Issue 809 in API Issue Tracker.
There actually is what we can call a “implicit model context” when there is no selection and that this implicit context is the top-level model entities collection.
Evidence that the Invert Selection command actually becomes a Select All command and selects everything at the top-level of the model.
I can’t remember offhand what it was I thought would be nifty on such a no selection context menu. (I’ll sleep on it.)
It actually does not have a conditional to ensure it shows when the selection is empty. I.e.:
module RtClick
if !defined?(@ui_loaded)
UI.add_context_menu_handler do |menu|
if Sketchup.active_model.selection.empty?
menu.add_item("It's Empty") {
UI.messagebox('Really Empty!')
}
end
end
end
end
But it still does not appear when the selection is empty.
Weirdly it does with a right-click on any axis.