[Productivity] Additional Checkbox "Viewed" next to tree item

[pascalschumann]

Thank you for your plugin, it's very useful. I suggest the following productivity improvement. Most of files in pull requests contain only few changes (e.g. package move/renaming). I can check it with a glance, but currently I must move my mouse to the right side. The idea is to have another checkbox right to the clicked tree item. Thank you.