Hide window outline when window is maximised

[sylveon]

On a normal Windows 10 window, the colored outline is visible only when the window is not maximised.
When it is maximised, there is not outline

Actually, the colored outline is shown even when maximised in the skin:

Steam should respect that behavior, for more consistency (and also because colored outlines looks ugly when maximised)

[Edgarware]

The skin has no way of telling whether the window is maximized or not, so this can't be done.

Technically speaking the outlines are already non-consistent, since the outlines for Windows 10 apps are slightly transparent (hard to notice when it's one pixel wide) and steam doesn't support window transparency. This is part of the reason they're not enabled by default.