Created attachment 6415 
Win 10 panel

Looking forward to GTK3 Xfce, screens with higher resolution I think XFCE must allow to use larger panels with comfort (36,48 px) The only thing that prevents using them are some plugins (XFCE4-power-manager-plugin, XKB plugin, Pulseaudio plugin, Sound mixer plugin and maybe others) which are asociated with tray, but in fact are not tray. Tray icons on large panel will still be small (22-24 px), as we are used to see them, but these plugins will get extremely large.

I see two solutions:
1) The bette one: allow inserting panel into tray (So there will be panel with tray plugin, where tray plugin cintains another panel)
2) Allowing to change icon size for some plugins.

See also 12037