Offtopic: Single-header window management and layouting library

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For about 10 years I'm repeatedly running into the issue of window management and layouting (Windows graphical shell, unix X11 windowing, Mac OS X windowing, in-application windowing like in Nuklear, mobile systems windowing, etc.). There are plenty of window managers, window managing applications, layouting algorithms, guidelines for mobile-friendly windowing, standards (EWMH, ICCCM, etc.) and related stuff. But it's everything a mess, wildly differing, not multiplatform, not transferable, too dynamic (what works now will soon stop working), each solution offers only a subset of the needed/expected functionality, and most of them are mutually incompatible (combining of several existing solutions doesn't work at all or not well enough).

And because I'm convinced, that windowing functionality shouldn't be part of a GUI library and at the same time should be fully multiplatform, I recently got an idea of a single-header library providing a minimalistic interface for the following three domains of functionality.

1. Means for setting high-level abstracted behavior and properties and for each also it's defaults (e.g. new windows will appear there and there and will have this and this frame with these and these attributes).
2. High-level abstracted triggers of all kind (e.g. a new window appeared and you can access it through this pointer/structure/object/...).
3. Interfaces for several wide-spread standards (EWMH, ICCCM, etc.). Inclusion/exclusion of these shall be configurable through similar means as NK_INCLUDE_* in Nuklear.

(with high-level and abstracted I mean mostly things initiated by the user and by to-the-user-visible issuers like some remote or scheduled commands etc.)

What do you all think about this? Would you use such a library or rather stick with an own half-baked solution?