There’s an update of Default Folder X available at https://www.stclairsoft.com/DefaultFolderX/release.html
It addresses several bugs, one of which is fairly significant: Save sheets could get “stuck” for up to a minute under some circumstances. It also won’t complain about the QQ chat application being incompatible if you’re running QQ version 6.1 or higher – Tencent fixed the compatibility problem in their 6.1 release.
If you’re running Default Folder X 5.1.6 or using macOS 10.13 High Sierra, make sure to download Default Folder X 5.1.7 now!