Acer have made some alterations to the xfce4-panel, you probably noticed that you can’t right click and add launchers.
Edit: For anyone who came here to find out how to enable the “advanced menu” or XFCE menu on right click – Open your documents, click “File->Terminal” and type “xfce-setting-show” or just “xfce-se” then hit tab. Click “Desktop->Behaviour” and then tick “Show desktop menu on right click”.
I have a workaround but haven’t worked out why yet. Open a terminal (from a Thunar window if you haven’t enable the right click on the desktop). Now if you look in .config/xfce4/panel there is your standard xml file to layout the panel. If you alter this, on relaunching the panel it overwrites it with the default.
The odd thing is that the un-patched panel is still there, and works as normal (look in /usr/bin – there are two panels, one renamed xfce4-panel.old). Well for some reason that I haven’t fathomed, if you kill the running panel then alter the config then run xfce4-panel.old then restart it the xml config is not overwritten.
Here’s a screenshot: