I installed the package mozilla-firetray-thunderbird, but there won't be any icon in the notification area, when closing thunderbird. Instead, I can see the name "Thunderbird" when hovering with the mouse pointer (see attachment). This way, I can't reopen thunderbird once it is minimized to the tray, because you can only reopen those apps in the notification area by clicking on their icon (unfortunately).
I tried to use an icon from /usr/share/icons/hicolor/, but this didn't change anything.
Any solutions/experiences regarding this issue?