I use snip (Win 7) all the time. Never had a problem. Try using snip not on Firefox. Is the problem still there?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Thanks for that. It is still a problem but it's probably clear that this is a Windows 10 problem. Also, when Mozilla did a guess about my system it didn't notice my OS is now Windows 10 and guessed Windows 7. What does that mean?

This was detected as you where starting this question thread. User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0

Compatibility setting in Win10??

Thank you, but I don't know what compatibility setting in Win 10 is with regards to Snipping Tool, which is an accessory of Win 10. It should be compatible with itself, shouldn't it?

I use Windows 7, but Win10 is probably pretty much the same with this.

Right-click the Firefox desktop icon and open Properties. Then look at the Compatibility tab and view "Run this program in compatibility mode for:"

Is Windows 7 is selected?

Hello again. I've since discovered that Snipping Tool won't work with any screen or file. It is obviously a Windows 10 problem on my particular machine because I've had other reports in a MS Community forum that others have no problem with Snipping Tool.

I'll just have to wait and see... can't waste any more time on this.

Thank you for your kind efforts to help. Peace to you and your family.

Go to the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for what you want.