Jittery tabs
Tabs are 'jittery' on xfce4-terminal, mate-terminal, thunar and many other gtk3 apps. To recreate, open multiple tabs, then switch between them using Control+PageUp/Control+PageDown. The tabs will change in horizontal size slightly sometimes when toggling between them.
The fix is to remove lines 2787-2790 in gtk-3.0/gtk.css:
sudo sed -i -z 's/ *notebook > header.top > tabs > tab:checked:not(:last-child) {\n *margin-right: -3px; }\n *notebook > header.top > tabs > tab:checked + tab {\n *padding-left: 9px; }//' /usr/share/themes/Breeze*/gtk-3.0/gtk.css
Edited by pkfb cedkrz