Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Sorry, I am alwabys in "Default" theme, and the "Edit" function has worked perfectly until the last update. I am only using two add-ons as it is.

Specifically, I have in the past used the "Edit" feature to copy a website in one tab and paste it into an email I am composing in another tab, thereby creating a link in the email. Now, when I "Copy" the website, the highlighting disappears, and nothing is ever "Pasted" anywhere ever again.

Again, this worked perfectly before the most recent update. Is there a way for me to regress backwards to restore this function?

And, now Editing is working perfectly again. Thanks for your help, although I am not sure that either of us did anything we could repeat.

Thanks again for your help.