If you need to work file based and not project or directory based then you should probably be using Kwrite, which literary is a stripped down version of Kate specifically for this purpose.
Which shows how far ahead KDE was even in 3.5 times with reusable embeddable components that were highly engineered. For example Konqueror has a long list of plugins including calling kwrite to render inside of it. The early kio tooling that predates fuse in having universal access through a single file viewer.
And it seems konqueror is the only browser today that can split a tab into multiple panes! I used this a lot in 3.5 times. It still works, just need to file another bug report for sane dnd behavior..