Yaru: Fixes and tweaks for the theme

[madsrh]

• [X] disabled checkmarks & radio buttons gray
• [X] change checkmark to Vanilla style
• [x] Filemenu background should be gray -> #1734
• [x] hover color for blue checkmark & radio buttons should be more visible
• [x] Remove aubergine from the GDM Cancel button (Shell)
• [x] Yaru 1.0 style tabs
• [x] Menu borders contrast to the area it is drawn on in the dark theme are not strong enough
• [x] 0.5% or 1% lighter buttons (for the headerbar buttons)
• [x] adjust the scale assets to the new colors (also the new focus color ;) )
  Implement new design for switches
  Edit by @Feichtmeier : after the design call with mpt we agreed on keeping the switch design as it is
• [x] no borders for checkmarks in file menus and context menus
• [x] grabhandels in the dark theme should be brighter (upstream: https://gitlab.gnome.org/GNOME/gnome-control-center/issues/858, see #1847 for more info)
• [x] Combobox menu’s edges are both 1 pixel too wide -> see #1849
• [x] Draw a new hand cursor for https://github.com/ubuntu/yaru/issues/855
• [x] NOT-FIXABLE; When a radio menu is opened, the text of the current item should be in the same place.

[Feichtmeier]

Eventually the check/radio hover is already fixed
What do you think @madsrh :
Normal:

Hover:

[madsrh]

IMO that looks fine

[Amr-Ibra]

Is this issue on the radar? https://github.com/ubuntu/yaru/issues/1423

[madsrh]

@Amr-Ibra yes! Everything is 😄 @ubuntujaggers is currently revisiting the cursor so perhaps he could take a look at this too?

[clobrano]

This list comes from the latest design fest, is only a subset of all the open issues and it is by no mean a complete list of goals for 20.04

[Neocazen]

Greetings team. Also change the color of the Spinner to orange or purple

[madsrh]

I'll close this issue. I've moved the last two open items into separate issues