Is there some API to create tooltips for user? I mean exactly same tooltip like if you hover over anchor tag and you can see its title. Some light yellow background tooltip with black text to inform user that he has activated or deactivated a command.
I didn’t look into the code, but this blog post about ‘Popup ALT Attribute’ sounds like it could be similar to what you need,
Doesn’t sound. I don’t need migrate, nor I use XUL. Nor I need alt attribute. Just tooltip like this https://i-msdn.sec.s-msft.com/dynimg/IC510746.png or https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/18942/versions/1/screenshot.png (prefered)
Form a SDK-based- or WebExtension the only thing you can do is to use a content script and add a <div> or <iframe> that contains your tooltip to the page.