Created attachment 4882 Screenshots Hi! I was set system panel icon size to 18px (first screenshot), but I got broken icon after system restart (second screenshot). So I have to run 'xfce4-panel --restart' to make it looks like 18px (third screenshot). I think after first panel start there is no resize action to icons.
Having the same issue with MEGA sync application. Here details: https://github.com/meganz/MEGAsync/issues/25 Regards.
This is a general problem with systray icons. The panel has very limited control over their icon size... As we consider the systray somewhat legacy I don't think we'll ever fix / improve this.