switch from user-side. mean: if user will symbolic icons on panel, all good, if user will regular icons on panel, he can add: # /* xfce4-Panels button-style */ .panel { -gtk-icon-style: regular; } # to the gtk-contained.css in /usr/share/themes/"Theme-name"/... or in ~/.config/gtk-3.0/gtk.css .. then the better option to switch the used icon will be to check out ( in /panel-plugin/main-panel-plugin.c and/or in /panel-plugin/main-status-icon.c ) if gtk_theme_has_set to use regular style for icons, if not; then use the symbolic-icons for clipman-symbolic.svg else use the regular icons for xfce4-clipman.png .. not only check if icon exist on icon-theme .. i am not a coder, but i think a static setting to symbolic is not welcome on all user's themes so please forgive me this idea, if this not posible
I must say I don't understand what happens here but clipman icon (panel applet, not standalone application) looks kind of different of anything else: https://imgur.com/HnXZ1ET.png I just upgraded to 4.14, so not everything looks perfect yet... but... as you can see, for now I'm using oxygen icons. Oxygen has: cat oxygen/index.theme |grep Inherits Inherits=hicolor In hicolor there's: ./hicolor/64x64/apps/xfce4-clipman-plugin.png ./hicolor/24x24/apps/xfce4-clipman-plugin.png ./hicolor/scalable/apps/xfce4-clipman-plugin.svg ./hicolor/48x48/apps/xfce4-clipman-plugin.png ./hicolor/32x32/apps/xfce4-clipman-plugin.png ./hicolor/16x16/apps/clipman-symbolic.svg ./hicolor/16x16/apps/xfce4-clipman-plugin.png I found following desktop files: [root@linux apps]# pacman -Ql xfce4-clipman-plugin |grep desktop xfce4-clipman-plugin /etc/xdg/autostart/xfce4-clipman-plugin-autostart.desktop xfce4-clipman-plugin /usr/share/applications/xfce4-clipman.desktop xfce4-clipman-plugin /usr/share/xfce4/panel/plugins/xfce4-clipman-plugin.desktop All of them say that: Icon=xfce4-clipman-plugin However, my clipman plugin uses ./hicolor/16x16/apps/clipman-symbolic.svg I'm not 100% sure, but isn't it a bug?
The icon that is used is by default just called "clipman-symbolic", so if your icon theme contains an icon by the name "clipman" and you add those lines to gtk css it should work. See also this duplicate issue for reference: https://bugzilla.xfce.org/show_bug.cgi?id=13408