Comment 0 for bug 1729340

Since Ubuntu 17.10 Header Bars (and title bars) use inverted styling when a window is maximized.
AFAICT this is for better visual integration with the top bar gradient.

Transitioning from the top bar gradient to the header bar gradient is a good choice,
though it changes meaning for tab selection, for example in GNOME Software where
the UI is split into several tabs, making the visual appearance change perception
about which tab is actually being represented as "selected".

This means that in normal state, the selected tab appears to be pushed inwards,
where as in maximized state the selection looks pushed outwards, which makes using
these types of applications kinda odd.

I see 2 ways of solving this:

* Revert the change of visual inversion of header bars in maximized state, but invert the Shell Top Bar gradient instead
(I can see design and philosophical reasons to keep the top bar going from light to dark downwards, though..)

* Separate the visual representation of tabs within a Header Bar using color, contrast, etc. and keep it consistent between maximized and normal state.
This might be a good choice, but probably requires to adapt other types of Header Bar widgets in the same way.