How to install new brushes in the Krita open source paint software, version 4.1.1, which I'm currently testing. Previous install methods for downloaded brushes, suggested by others, no longer work or else don't work in the same way.
A note on the .KPP format: It also appears that Version 4.1 no longer supports .KPP format brushes, which was the format that various brush packs on DeviantArt used. I tried hard, but could fine no way to import such brushes, and even manually pasting them into C:\Users\USERNAME\AppData\Roaming\krita\brushes didn't get them to load in the Krita interface. Nor did just dragging and dropping them onto the Brush palette. It seems a pity, as people put effort into their .KPP brushes. Perhaps there's some converter freeware to convert the old brushes to the newer formats, but I didn't find it. I've had to take out two bundles from my DeviantArt "Favourites" because of this problem, as I don't want people trying to install defunct brush sets in the latest Krita.
Test file: Wolthera's Inking Pack for Krita (now updated as an install "bundle" for Krita 4.x), and Filter Bundle for Krita.
1. Open the Krita 4.x. software in Windows. On the top menu, click Settings | Manage Resources...
2. The Manage Resources panel will open. There, select Import Bundles, select your downloaded bundle, have it show up in the relevant window, and then press OK.
3. Right-click on any bit of empty space on the Palette menu, and select Brush Presets (if you don't already see them). The Brush Presets palette will appear. You may want to tear off and re-size the Brush Presets palette, so that you can see all the Brushes you have in a single glance.
4. Now to find those brushes you just imported.... Well, that's easier said then done, and you may to hunt them down. They don't just go into a neatly separate folder marked "New Brushes from the Web", and instead they just get appended and jumbled into your main default brushes set. Nor are they always searchable via the maker's name. As, in this case, 'Wolthera' doesn't work as a search while 'Filter' does. Nor can you shift-select multiple new brushes and 'Tag' them.
Given these clunky difficulties in brush management and finding, it's going to be easy for the new Krita user to get into an almighty tangle if they load up on a lot of imported brushes from the Web. It seems safest to just use the defaults, and only a couple of bundles - such as Wolthera's Inking Pack.
It would be much easier if the makers of Krita could enable the following in future: 1) Open Brush Palette; 2) Make new sub-folder or tag there (such as 'Brushes from the Web'); 3) then just drag-and-drop the downloaded bundle into the new folder/tag.