Galaxy is out-dated, not maintained, and has on SVG support. So we should replace it with a complete set, once Colibre contains all items.
Since Industrial is also not maintained (and for some reason not listed under Tools > Options > View > Icon Styles) the proposal is to clean-up the function a bit further.
Patch at https://gerrit.libreoffice.org/#/c/52118/
I can understand there is a need for cleanup or anything else but i dislike breeze; sfr and also Colibre. I am art lover and love some 3d and not flat design because of plasma and other design form. So i hope tango can be saved as icon style in tools => options => view => icon style
The plan is to make the legacy themes available as extension. But since there is no maintainer Tango's days are numbered.
Valid enhancement request.
Best regards. JBF
*** Bug 116916 has been marked as a duplicate of this bug. ***
Colibre has now ALL tango and galaxy icons included.
3.300 icons + 1,500 linked files = 4.800 icons
3.900 icons + 150 lined files = 4.050 icons
+1 to proceed
And IMHO believe the work integrating Karasa Jaga  3D to core (bug 117342) would compliment this change, for those inclined toward 3D themes, and effectively permit us to retire Galaxy and Oxygen (to a legacy by "extension" status as Heiko promotes).
Done with https://gerrit.libreoffice.org/#/c/53092/
(In reply to Heiko Tietze from comment #0)
> Galaxy is out-dated, not maintained, and has on SVG support. So we should
> replace it with a complete set, once Colibre contains all items.
FYI, Regina is still maintaining Galaxy and choosing a new fallback isnt just whether it has all items, it should also depend on how well the fallback appears in the child themes and how tested these icon metaphors compare with the previous fallback.
The idea was to have Colibre for windows users, as it had all items from galaxy (also available in svg) and the feedback was very positive Colibre was choose as fallback.
I don't see any reason why Galaxy shouldn't be replaced as fallback theme.
I wouldn't obsess about it and go with Colibre as fallback icon set for the OS it's planned to use it for all systems.
If it works not well and many complains come from users, we can revert it.
*** Bug 118123 has been marked as a duplicate of this bug. ***