philippgfx

You would set the page size in your document to 99x210 then when printing set the paper size in the print dialog to A4 and the document model to "N-Up".

Like this? If you want a PDF from, just print to a PDF driver

Please see the help about grids. On the Home screen, tap the question mark icon to view the Affinity Designer Help, type grid in the search box and then tap on ‘Grids’ in the list of search results.

I'm bumping this as I have the same request. It would be nice to group slices.
 
philippgfx, you can sort the slices, just not by drag/drop though. You need to use these buttons on the top right corner of the window, in the Export Persona.

Hello,
 
I have some projects with many icons that need some variants for scaled resolution (@1.25x, @1.5x, @1.75)
for pixel perfection I need to create the variants manually and end up in a large list of slices.
 
It would be very nice in this scenario to be able to sort the slices (currently the slices are sorted in creation order only)
and it would be good to be able to group the slices in folders to have a better overview.

Wow, thanks. Order has been placed :)

cmd + v doesn't work when editing the name of your slices in the export persona. Right click and choosing paste works but is a pain ;)

@ronnyb you're right about the grid color.
I'm helping me out by using a separate (locked) layer with a rectangle filling the complete page to have a darker background color.