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Just to add to the discussion, for those users in Kubuntu, there are plenty of options to configure a shortcut to open Tabs Outliner itself. Go to the "Special window settings" of Tabs outliner's window, and enter the following settings:

- Window class (application): exact match, google-chrome

- Window title: exact match, Tabs Outliner

and then you can define several behaviours:

- remember size and position of the Tabs Outliner's window in "Size & Position" tab

- set a specific keyboard shortcut for Tabs Outliner's window in "Arrangement & access" tab.

Hope that helps.