The Tango theme is the most complete icon theme and it's most in line with
OS defaults (Mac OS, Windows, most GTK-based desktops). Tango's goal is to
provide a consistent icon look across various platforms, while Oxygen is
specifically designed for KDE and often feels out-of-place on other
platforms, which is why it's preferable to keep it default only on KDE.
It's true our current icons look outdated. That's not a fault of the Tango
specifications -- Gnome and elementary have been able to produce beautiful
modern icons based on those specs.
We were planning to update our icons as well based on Gnome's icon set,
but, unfortunately, the volunteer who lead the project doesn't have time
for it anymore. The project is at
https://github.com/libodesign/tango-testing. If you'd be interested in
picking it up, that'd be great.
There's also an effort to produce a flat monochrome icon set, which is lead
by Issa Alkurtass: https://github.com/libodesign/flat-icons. That one's
being actively worked on, but it has a long way to go before it has all the
icons that the Gnome icon theme has.
> After installation, we see old Tango icon theme
> (for example, in LibreOffice Portable).
> We could have a bit more modern like view just
> by using Oxygen icon theme (maybe in LO 4.1).
> I created a proposal in
> https://bugs.freedesktop.org/show_bug.cgi?id=64670 >
> Mindaugas B.