Comment 3 for bug 247944

I think you're right - this is a bit confusing. I would expect the icon to disappear after locking the packages too, so I'll confirm this.

Steps to reproduce:
-Lock all upgradeable packages in Synaptic

What do you expect to happen?
-Update notifier icon should disappear from the notification area once all upgradeable packages are locked.

What actually happens?
-After locking all upgradeable packages in Synaptic, the Update notifier icon remains in the notification area. It doesn't disappear until you right click on the icon and click 'Check for updates'.

Some info:
chr1s@chris-desktop:~$ lsb_release -rd
Description: Ubuntu 8.04.1
Release: 8.04
chr1s@chris-desktop:~$ apt-cache policy update-manager
update-manager:
  Installed: 1:0.87.29
  Candidate: 1:0.87.29
  Version table:
 *** 1:0.87.29 0
        100 /var/lib/dpkg/status
     1:0.87.27 0
        500 http://archive.ubuntu.com hardy-updates/main Packages
     1:0.87.24 0
        500 http://archive.ubuntu.com hardy/main Packages