Maybe the new "Open with Nightly" entry could be moved to the "Open with" entry?

Instead of "Microsoft Edge" (or whatever program is used for viewing pdf) it should show "Firefox" as a default to open a pdf file.

This would avoid the additionally entry.

If i want to open a pdf inside Firefox, i then choose "Open with Firefox Nightly".

We decided to put it as a separate option to not break muscle memory. We are planning a new design for the dialog which will lower the number of clicks needed. In the case of your screenshot, when Firefox is the default already, we could possibly hide the new option.

(In reply to Jared Wein [:jaws] (please needinfo? me) from comment #1)

We decided to put it as a separate option to not break muscle memory.

Could the "Open with Nightly" option moved under the "Open with" option?

I think, it would look better in the dialog.

When the new "Open with Nightly" option is available it is checked by default so it makes more sense to place it at the top.

.

(In reply to Jared Wein [:jaws] (please needinfo? me) from comment #1)

We are planning a new design for the dialog which will lower the number of clicks needed.