@Coises said:
Curiously, because this current topic is really focused on “Way to tell if clipboard has column-block in it before pasting?” (from its title), it doesn’t, until @Coises posted, reference MSDEVColumnSelect.
However, these topics do:
https://community.notepad-plus-plus.org/topic/17272 Mar 11, 2019, 1:28 PM posting
https://community.notepad-plus-plus.org/topic/19643 Jul 9, 2020, 1:56 PM (in script listing)
And, Scintilla code discusses it, too, HERE.