Are you talking about Adobe Reader? can you elaborate your question?

I think what is happening is FF is popping up Microsoft Edge as PDF reader and all PDF's are in Edge tabs.

I don't really want to use Edge at all.

I just did a test using a pdf in FF. It came in a FF tab which is what I want.

But since my question, I have also been playing with file associations in Windows. .pdf is now set to Edge.

I don't understand why the Edge icon doesn't show when Edge is running.

I would prefer Adobe Reader as the default W10 pdf reader. But I don't seem to have that.

On Microsoft App store they have Adobe Touch Reader, but that dos not work very well on a Dell XPS13.

In the end, not very much to do with FF. But rather all these competing PDF readers competing to do the same thing.

I need to choose, then configure a 'clean' PDF reader setup.

I am not there yet

Anyone with perfect solution that has all features?

See also:

• https://support.mozilla.org/en-US/kb/view-pdf-files-firefox
• https://support.mozilla.org/en-US/kb/disable-built-pdf-viewer-and-use-another-viewer