Ubuntu – Unity notifications messed up after installing Gnome

Change the notification's mouse- over behaviour

Almost what you asked for, and possibly what you might like, a tiny, very light background script (no noticeable load to your system whatsoever, if no notification runs, it will only wait/check for one to appear) that will change the mouse-over effect of the notifications from fade:

to disappear (close):

This will only take effect if the mouse is moved from outside the area into the notification area, to make sure you won't miss the notifications if your mouse already is in the notification area if the message is launched.

How to use

1. The script needs xdotool

   sudo apt-get install xdotool
   

2. copy the script below into an empty file, save it as manage_notifications.py

3. Test-run the script by the command:

   python3 /path/to/manage_notifications.py
   

   with the script running, open a terminal window and run the command:

   notify send 'This is a test'
   

   now move the mouse to the notification. Instead of fading, it should disappear.

4. If all works fine, add it to your startup applications: Dash > Startup Applications > Add the command:

   /bin/bash -c "sleep 15 && python3 /path/to/manage_notifications.py"
   

The script

#!/usr/bin/env python3
import subprocess
import time

w = int([s.split("x")[0] for s in subprocess.check_output(
    ["xrandr"]).decode("utf-8").split() if "+0+0" in s][0]
        )

def get_mouse():
    loc = subprocess.check_output(["xdotool", "getmouselocation"]).decode("utf-8").split()[:2]
    return [int(n.split(":")[1]) for n in loc]

while True:
    time.sleep(1)
    try: 
        subprocess.check_output(["pgrep", "notify-osd"]).decode("utf-8")
        curloc1 = get_mouse(); t = 1
        while t < 10:
            time.sleep(1)
            curloc2 = get_mouse()
            test1 = curloc1[0] > w - 400 and curloc1[1] < 400
            test2 = curloc2[0] > w - 400 and curloc2[1] < 400
            if all([test1 == False, test2 == True]):
                subprocess.Popen(["pkill", "notify-osd"])
                break
            curloc1 = curloc2
            t = t+1
    except:
        pass

There isn't any command for retrieving previously send messages in Desktop Notifications Specification so my guess is that they are discarded after retrieving.

You can however observe these using dbus-monitor command, like this:

$ dbus-monitor "interface='org.freedesktop.Notifications'"

Sending simple notification:

$ notify-send "Hello there"

results with following information:

method call time=1555095758.597788 sender=:1.385 -> destination=:1.386 serial=6 path=/org/freedesktop/Notifications; interface=org.freedesktop.Notifications; member=GetServerInformation
method call time=1555095758.601101 sender=:1.385 -> destination=:1.386 serial=7 path=/org/freedesktop/Notifications; interface=org.freedesktop.Notifications; member=Notify
   string "notify-send"
   uint32 0
   string ""
   string "Hello there"
   string ""
   array [
   ]
   array [
      dict entry(
         string "urgency"
         variant             byte 1
      )
   ]
   int32 -1
signal time=1555095765.734845 sender=:1.386 -> destination=:1.385 serial=15 path=/org/freedesktop/Notifications; interface=org.freedesktop.Notifications; member=NotificationClosed
   uint32 1
   uint32 1

Time field is an UNIX timestamp, can be translated like this:

$ date -d @1555095765
Fri Apr 12 21:02:45 CEST 2019