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At minimum, you have a screen coordinate space (which is almost never what you want to use), a window coordinate space, and a Compose root coordinate space. Each of those can be measured in dps or pixels, and sometimes it matters if those pixels are integers or floats.

And then every single node has its own local coordinate space, after layouts and padding and scrolling and translations are each applied. Keeping track of what coordinate system you want to be working in is tricky when you start having complicated interactions that move across boundaries.

Mental translation between different coordinate spaces is tough. I somehow keep running into this problem in every other project. I wrote this while dealing with multiple windows in cascade: github.com/saket/cascad...