For instance, if you are typing $SensitiveMessage, you would be far better off doing that in a firefox 100 textedit box in a browser tab, rather than an xterm, or emacs, or your desktop environments preferred text editor, or anything else.
I currently use "secure keyboard" in xterm but I know that has problems.
It has to make a Herculean effort because it is by far the worst possible app to be typing $SensitiveMessage in.
At least Kate or gedit probably doesn't have a second tab open running a JavaScript subprocess which is presently trying to attack you so it can cryptolocker you or empty your wallet.
So it's only more secure if you think emacs / xterm / your text editor is real likely to be compromised
FF devs are finalizing a utility process overhaul and laying the groundwork for CFI; for years, Chromium has had both with a much more thorough implementation than FF will in the near future. However, the browser space desperately needs competition so I'll take what I can get. Sigh.