Back in December I gave up on Debian and Iceweasel and am now using Kubuntu and Firefox. I was getting along OK for a few weeks and then I did some updates and ‘‘Check my speling as I type’’ no longer works on some websites including SD. I go to Edit/Preferences/Advanced/Browsing and the box for spell check is checked. I note I have a close button, but no OK or Apply buttons.
Well I just fixed the problem. If anybody else is interested, right click in the text box, click on Languages, click on English/US or whatever you choose.
I apologize for all my misspellings in the last month.
Now if I can figure out how to make the page up and down keys work.