Native notifications not working on Ubuntu Linux

[diegobersanetti]

Your DownThemAll! and Browser Version and Language and Operating System

DownThemAll! v3.0.8
Firefox 52.0.2 64-bit en-US
Ubuntu Linux 16.04.2 (kernel 4.4.0-72)

Expected Behavior

DTA notifications should use the OS's native notification system (notify-osd/libnotify on Ubuntu Linux)

Actual Behavior

DTA uses instead some "alert boxes"

Steps To Reproduce

Trigger any notification (download added / all downloads completed / etc.)

Additional info such as log extracts

Please enable Diagnostic Logging in the Privacy tab of the DownThemAll! preferences and either copy/paste essential part of the log or attach the entire log. Please note that the log may include sentitive information which you have to remove prior to posting it!