I was looking for an extension to do exactly this. I always have my chat (Slack/IRC/Mattermost) in it's own window on my second monitor, but i like opening everything my main monitor, and this is exactly what I needed. Thank you Piro!

Works, but, ideally is used with a side bar.

write adoutyour experience wits this add_on

This tool is a very valuable tool in my arsenal. It is effective in my fight with "tab addiction". I am easily distracted, to the point of disability. In the past I have used open tabs in Firefox as reminders of what to do and look into so I don't forget. The problem is that I get too many tabs open and Firefox bogs down. This allows me to keep matters of interest available as a list of bookmarks in a separate visible list while still enjoying the hierarchical nature of "Tree Style Tabs" another great plugin by the same author. This tool is truly a blessing for those who are struggling with managing the collection of things they need to think about and do.

No issues. Works well with TST!