Inconsistency in Header Bars between Maximized and Normal windows states

[Alfred E. Neumayer]

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 multiple 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.

[Daniel van Vugt (vanvugt)]

I agree. In fact I was wondering about the wisdom of inverting the button gradients when Marco was talking about it a couple of weeks ago...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Alfred E. Neumayer (beidl)]

Additionally, taking GNOME Builder (from the Ubuntu archive) as an example: the window always uses the inverted gradient, without having to maximize it. Might be due to Builder adding another CSS class called "workbench" to its main window (GTK_DEBUG=interactive), throwing off GTK somehow.

Putting myself in the mindset of an app developer who wants to target different distros with different default themes, I'd be rather confused.