If this sounds like your week
“Always on top” is a table stakes feature that most stacks still get wrong.
Too heavy, too modal, or too web.
Where tooling usually breaks
You do not need a compositor lecture to park a spec sheet on screen.
You need a small app that is honest about the job: pin the window, let you work, do not get in the way of input.
On top, not in the way
Main window: where you type PinPoint window: the reference, pinned Focus: your editor, not a fight with z-order