UPDATE: There is no way for the add-ons to cache an internet icon as far as I know. Please let me know if you saw that implemented somewhere.
Possible solutions are:
1. You can download the icons on your computer and in the Add-on Options page specify the local icon file address for each row. The local address should be specified like "file:///C:/icons/myicon.ico". The standard icon address on the internet is http://www.(DOMAIN).com/favicon.ico . So for google it is http://www.google.com/favicon.ico
2. I can supply some icons with the extension. But this will not cover all the websites.
3. I will implement the "Disabled icon" option as you suggested.
Please let me know if you have other solutions or suggestions.


Thank you for the bug reporting.
The issue is fixed now in v5.18.
There is no need for an extra option.