Plugin that shows which apps are currents running

Multiple plugins including Status Notifier and Status Tray

Issues relating to the icon that appears in the notification area, aka status tray, for apps

Settings found on the Display tab of the Panel Preferences dialog

Settings found on the Appearance tab of the Panel Preferences dialog

Languages that write RTL including Arabic, Farsi, Hebrew, Urdu

When a custom dpi is set in the the font tab of Appearances dialog

System tray icons that are set as hidden in properties and appear behind an overflow arrow in the panel

Issues related to when the background style

xfce4-popup-applicationsmenu