Is it possible to hide all tuplet brackets? I have not found this option…
You can change the default options for showing tuplet numbers and tuplet brackets on the Tuplets page of Engraving Options.
Loff56’s question still remains: In a series up tuplets, how does one show numbers for the first couple and for none after that? Deselecting them one by one isn’t really an option and deselecting them all in Engraving Options isn’t either.
The answer is that you would select the tuplets whose numbers/brackets you want to hide, and hide them with Properties. I’m not sure why you consider selecting them and setting properties not an option, given that it’s reasonably easy to select a bunch of them at once and then simply change a single property.
In a passage with not only a series of tuplets but all kinds of other elements like slurs and dynamics, how one would select only the tuplets in that region? For one thing, you have to do this in Galley View, as drag-selecting a contiguous group over several systems in Page View seems impossible. For another, you can’t drag-select tuplet numbers above and below the staff without selecting everything else, so you have to Cmd-click all the tuplet numbers one by one. A logical choice might be the possibility of selecting the first tuplet number and then shift-clicking the last one to select all the ones in between. This would be a handy program-wide feature for selecting all elements of a certain type in a region.
In Brackets options, “show tuplet brackets”, I have 2 options : “Show only when necessary” and “always show”. Is it possible to add “never show”? Thanks a lot for your job!! 
Dear Vaughan,
this comment is supposed to follow your comment…
Or implementing a filtered selection… but I think this option is already in the pipeline, isn’t it ?
I certainly hope so. This could conceivably aid a number of operations involving other types of objects. In any case, this would be the best way of dealing with the tuplet situation I already described but which wasn’t really addressed. It’s not uncommon to start a long passage of tuplets with the first few showing and the rest not, since it’s no longer necessary to keep stating them and it reduces clutter. In Dorico, the current methods are either to remove the redundant tuplet numbers one by one or to change the default not to show tuplets at all and then to change the first few in the properties panel to show the numbers. The first option will take a lot of work and the second removes all tuplet numbers in an entire document, making it’s easy to miss seeing them when proofreading if you do want them to show.
+1 for the filtering option, but this I am also sure is already worked on.
I changed the default not to show the numbers and tried to activate them in the first bar of my piece only. I did not find the option to show them - not in write and not in engrave mode, activating beams, single notes, group of notes, all together. How do I do this - or did you just assume that this is possible?
Thanks!
It almost seems like Dorico ignores the tuplet when you hide the number in engraving option. The tuplet options are indeed gone. Also - if you copy eight note tuplets without the number, they paste as normal eight notes 
Daniel,
Is there way to hide «both» numbers and brackets?..
…as «camouflage» use in case of 6/8 against 2/4 as shown here !
Of course will be easier when Dorico will support real independent time signature.
Thanks for tips.
Dorico is simply wonderful !
I made it with these settings in the properties panel:
Yes, you can certainly hide both number and bracket via Properties, but you really should keep View > Signposts > Tuplets switched on, so that you can select the tuplet signpost along with the notes when you copy and paste, otherwise you will only paste the notes from inside the tuplets rather than the tuplets themselves (which is a feature, rather than a bug, for the avoidance of doubt!).
This makes sense. But what about when the number is hidden in engraving options? Maybe this also should display the signposts?
Yes, it should. I’ll make a note of this.