is it possible to create a progress bar on unity panel, like this?
it could be done with unity launcher api (https://wiki.ubuntu.com/Unity/LauncherAPI)
progress bar might display overall progress for playlist or for each song.
popup menu might display the song list.
is it possible to create a plugin or a script for this purpose?
or this subject should be posted in the suggestions?
I suppose it is to improve usability 8)
First your link refers to unity3d which is a game engine totally unrelated to the unity desktop.
Second, the unity desktop seems to be a bit abandoned.
I think unity use the appindicator library for that kind of thing, but I don't see anything related to progress bars, so I don't know.
If you find a library that does this and it has a typelib file (typically put in a gir package such as gir1.2-appindicator3-0.1) it should be very easy to add.
this is my fault! :o I corrected the link.
officially, unity is abandoned, but thanks to the unity team this package
is still in development (latest update (https://launchpad.net/ubuntu/+source/unity) was in April 2020)
compiz and its plugins were also rewritten a year ago and got back
all the functionality which they lost before.
there is no problem to change desktop environment to unity on the modern
versions of ubuntu, so I think all unity lovers (as me) can use it flawlessly.
as for library, there is nothing to do with appindicator which provides support
for tray icons, while I'm talking about the launcher icons (please look
at the image and at the corrected link in OP).
It's made through libunity API calls, and python wrapper is provided as well.