Adrian Page in one fell swoop — but it must have been a lot of work — make Krita use OpenGL for rendering. Krita still works without OpenGL, but OpenGL opens the door to really cool and fast filters, really interesting tools and great performance. Moving layers is now smooth and precise. All the interesting paint applications on Windows use OpenGL — Art Rage and Deep Paint, for instance — but I don’t know of any paint or image editing application on Linux that offers this. It also means that Krita images now can have transparent areas when embedded in other KOffice applications. It used to be that if you had an image with transparent areas, you’d see the gray blocks, instead of the background of the embedding documents.
And, deviating for a moment into Krita internals that are not important for users, but that make the developer’s life much easier, Adrian’s implementation makes it a snap to port this code to Qt4, and several changes improve the correctness of Krita’s rendering a lot.
There have been other improvements to Krita, too, recently. I’ve cleaned up the plugin system and made sure only plugins with the right version number are loaded, we have a docker tab with a dynamically updated histogram and new and very cool wavelets filter: