I would like to know if there is a way to create the same kind of a popup window that you can get with the API for toolbar button or address bar button described here: Popups API documentation Either achieved true the WebExtensions API or other means.
More specifically I do not need the window title bar or title bar buttons nor the address bar, forward/backward buttons etc. Like shown here:
According to the documentation you can create extension pages, but they do include title bar and title bar buttons - Extension pages API documentation
Like this one: 
Purpose: I have created my self an extension which adds a button to the contents of a specific web site. When the button is pressed it opens a new tab with a certain cross origin web page. I do not want to click around closing the opened new tab to go back to the previous. A pop up page here will make my life a bit easier as whenever you click outside of it - it closes.
What I tried: Tried opening the external web page as a modal <iframe>. But this leads to a CSP violation in the rare cases that I need to interact with it.
The used images are from the MDB web docs
