Firefox spell check plugin conflicts with Zoho

Firefox spell check plugin conflicts with Zoho

I have installed the spell checker plugin of Firefox. It will red-underline any unrecognized (misspelled) words in html - text areas, like in the current text area I'm typing right now. If I right click on an unrecognized word, it will show a list of suggestions.

Unfortunately, it doesn't work with Zoho or similar online text editors. The word is underlined, but if I right click, I get the right-click menu of Zoho.

I would like an option to show the original right click menu somehow, or have it extended rather then replaced as the rightclick menu is now.
I think this is a limitation of Ajax, but maybe there are solutions to it.