Nesse meio tempo, eu poderia resolver o mistério. Com a ajuda do ondoho do linuxquestions.org. Se alguém estiver interessado, aqui estão algumas informações básicas:
File: ~/.config/openbox/lxde-rc.xml
please have a look at that file. (warning! XML is hard to read without syntax highlighting!) the name might differ slightly, but you'll find it (*). you will notice that most app launch entries have a section that says something like this:
<startupnotify> <enabled>yes</enabled> </startupnotify>
startup notification is a mechanism that displays the background activity pointer until it is able to recognize that the application started. unfortunately, sometimes it is not able to recognize that, so the background activity pointer just stays there until it times out.
that's what you're seeing; it does not mean that there actually is any background activity, or that the launched application has a problem. it simply means that the mechanism that displays the background activity pointer is broken. and your system remains perfectly usable.
a small annoyance, but harmless.
Fonte: link