Flags from Linux Mint Cinnamon converted to Xfce-panel.
First you need to download and extract the contents of the archive. Flags are in the folder.
Then, you must open the file manager as super user. This is done by pressing the keys Alt + F2 and type in the field "gksu thunar".
Then go to "File System"/usr/share/xfce4/xkb/flags and paste flags from the downloaded folder to replace the existing ones.