Don't update it if it isn't necessary.

Otherwise, the screen would flash everytime, regardless of the setting
set by the user. I'm keeping the code
there in case I or someone else find a fix.

Gutenberg-related services (e.g., 'Online library') will now show an error message if they can't connect to the Internet and refuse to launch.

When an user first opened an ePUB, then a PDF, it didn't work. This was
due to an issue with the two tmpfs at '/kobo/inkbox' and '/kobo/run'.
This commit fixes that issue.

On this device, the Quit button makes the UI go beyond the limits of the screen when the menu bar is shown. Thus, the user will have to resort on the default Quit button found in MainWindow.