Custom page size for printing?

I need to print to a custom page size, but can’t find how this is done.
On Dorico 3 I thought I was able. Any suggestions?

You can set the page size for a layout in Setup>Layout Options>Page Setup>Page Size. If you export the layout as e.g. PDF, this is the size that’s used. If you print directly from Dorico, the paper options available depend on the printer selected - for instance, you can’t tell Dorico to print to A3 if the selected printer can only do maximum A4.

You should also find that if you have set up a custom paper size in Page Setup elsewhere on your system, provided that matches one of the built-in paper sizes that Dorico knows about (even if it’s not one of the ones that appears in Layout Options), then that size will appear as an option, possibly under another name, in Print mode.

I’ve been looking for this option, too, but unfortunately it doesn’t work. I have a custom page size set up (1920x1080 pts, for a 1080p screen). I need to make PNG graphics at this size. When I go to the Print mode and choose Graphics->PNG as the output, the page size dropdown is greyed out. It took me a bit to work out that I could switch to Printer, then under Page Setup, change the page size. But in that dropdown, there are only the predefined page size options, not my custom one. As a result, the preview is not quite right, and there’s no way to choose my custom size as the “page size”.
Thankfully the output is correct. (The issue is also discussed in this thread which is closer to my issue.) The reason the preview is important is that it’s a good way to check how the image will look without all the layout markings. One important piece for me is visual balance (including white space), and I can’t properly see that when the preview isn’t right. And, as in the other thread, it’s simply misleading to use page size options when the proper export need is a screen size.

Three suggestions for solutions:

  1. Short term: include pre-defined custom outputs for a 4:3 screen size (e.g. 1024x768pt) and 16:9 size (1920x1080), so that we can “trick” the preview into displaying the proper page size.

  2. Short-term: allow us to define a custom “page size” in the Graphics → PNG/TIFF section (or even just grab the currently defined custom size and use that, since that would solve the preview issue without all the work of #3 below).

  3. Long-term/Ideal: Treat the Print → Graphics tab as a proper graphics output section (e.g replace “Page Setup” with “Image Setup” or something more relevant, or even simply remove that in the modes that involve exporting to image (PNG/SVG/TIFF) so that it’s not so misleading by being a sort of hybrid section. PDF is a bit trickier, since it’s technically a file but it’s still centred on print page sizes. So there, it’s still relevant to have Page Setup options, even though it’s grouped together with the true graphics options in that dropdown.

I know it would be a big UI change to change the main Print mode tab, but maybe it’s better to think of Print mode as Export mode. I imagine actual printing is the majority of the use cases, but I also would think there are a considerable number of users who are exporting graphics for use on screen.