Whenever Firefox installs updates, the "Firefox addon updates" window is always on top of everything (highest in the z-order of all windows of all apps). Although it lasts only 10-ish seconds, it is very annoying (and unnecessary). Is there a way to suppress that? Thanks.
You can disable automatic updates for add-ons from within FireFox.
If you're using FireFox on Windows, navigate to... Tools > Options... > Advanced > Update > Automatically check updates to: ... and uncheck 'Add-ons'
For FireFox on Linux, navigate to... Edit > Preferences > Advanced > Update > Automatically check updates to: ... and uncheck 'Add-ons
You can then manually check for updates at a more convenient time by selecting: Tools > Add-ons > Extensions > Find Updates