Yes, the preferences are the first thing I was thinking to, but they allow one to choose a rule, and follow that one. On the contrary, I’m in a situation where the rules are often broken, so I would find useful a way to explicitly enter a natural while entering a note.
But I guess there is no easy way to be “anarchic” in Dorico, and exceptions are to be treated as they are.
The best bet is probably to set a keyboard shortcut to explicitly Show an accidental (this is definitely possible), then use it immediately after you’ve inputted each natural note. It should work fine even with the caret still active.
After another session, I have to say that having the natural entered in the same way of sharps and flats would be really handy.
I’m thinking to the cases where you only want it to cancel a preceding sharp or flat. Maybe a viable compromise could be to cycle between non-displaying and displaying. The first time you enter natural, it behaves according to the general rule. The second time, it is forced.
Its status might be previewed in the toolbox before entering the note, with a small mark in the Natural tool box.
On the German keyboard layout, I can press 0 and it will enter a natural accidental, and even forces it. Maybe you should allow the option to enter the accidentals after the notes are on the page in the note entry preferences?
Maybe this is what I’m looking for, so please let me ask more about it.
Currently, I have the Natural sign assigned to a key. I can press it before entering a note, and it behaves according to the rules.
If I want a natural sign that is not in the rules, I have to exit Note Input mode, be sure the note is selected, and press the key to add a natural sign. Then I can enter Note Input mode again.
Is there a way to do it without exiting from Note Input mode? @pianoleo 's solution above could be a viable one, if only I could see how to assign a keyboard shortcut to the Accidental > Hide option in the Properties pane.