Just tried it, works perfectly, I was also doing it for other nets/polygons and I was doing it a little different, I had All in the second part of the query, it worked, but now I understand the beast a tiny bit better.
Thanks for the help Free_electron and AJB.
i f you really want to unleash the full power of Altium : dig into filter expressions and manipulating the SCH list and PCB list viewers. Then hop into writing scripts. you can make this monster do amazing tricks.
I was comparing a new schematic (captured by hand from a customer PDF) to the bill of materials, earlier today. This involves a combination of filtering, sorting in the List, selecting the components you're checking, and comparing that listing to the spreadsheet -- say by copy+pasting the column into the spreadsheet and comparing the list, element by element, to see that they match up. Which checks that you know you have the right designators, and the right number of them. Then, since the listings line up, you can add the attributes wholesale to the components in the schematic with a single paste operation. A pain to set up, but very powerful.
Also, once you have that part list, filtering it again is easy: make a column beside the designators that formats it as "(Name = '<refdes>') OR", repeat for all <refdes>, copy the column and paste it in the filter box. After a few seconds of thinking, Altium determines your selection / mask.
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Afraid I don't have much to contribute to the thread, as it's already been answered...
I will add my preference though: I merely assign all via-in-poly as direct. As far as I know, the only downside to this approach is making them difficult to solder, if you should ever need to add a jumper/bodge wire to one. However, I also put accessible test points (which do form thermals) on all nets (near 100% nodal coverage), so I doubt that it's a big deal.
I also like to tent vias-in-poly, since it looks sexier. However, it is helpful to keep a few open, rather than tenting all of them, in case you need additional "accidental test points" shall we say.
Tim