I have upgraded to 17.10 (from very recent 17.04 clean install), and switched the Appearance back to 10.10 style - which means a (very) little editing of gtk3 and 2 files now that Colors option has disappeared from Appearance. Basically Radiance, icons from Humanity and then icons from Ubuntu's version of Radiance to get the orange, finally an edit to change the bg_color from green to orange for highlighting and scrollbars.
All good except for Software Boutique. The Bulk Queue, Search, Boutique News and Preferences button default to the color of the (light) background. Show white when hovered, as I'd expect - see attached screen shot.
What gtk color parameter is used for the default display of these icons please?
TIA!