Please add Rust syntax highlighting to KrViewer.
KrViewer syntax highlightning is provided by Kate (now moved to KTextEditor). Krusader 2.5.0 and later have Rust support as KTextEditor does. Does you Kate version supports Rust?
Yes, I have Kate (and KWrite) 16.12.3 with Rust support. However, Fedora 25 still provides Krusader 2.4.0-beta3. I'll wait for them to use 2.5.0 and for now configure Kate as the editor in Krusader.
I guess you understand that we can't do anything (about Fedora) here. (And Fedora Rawhide has a 2.5.0 package.)