The updated spell checker system is available in new comment system.
To use it simply click "Spell check" in the upper right corner of the commenting form after typing your comment. All the words written with an error will be underlined in red dotted line.
To see suggestions of the correct spelling click on the highlighted word and then choose the correct one. If none is suitable select "Skip word".
The spell check system can be turned off by re-clicking on "Spell check". The spell checker is turned on if you can see the green check under the icon "abc" and is disabled if the icon is highlighted green line.