If at least one specllchecker dictionary is installed, the spell check option and therefore the languages submenu, from where one can install additional dictionaries, becomes available. As described on the following documentation page in section Adding dictionaries: https://support.mozilla.org/en-US/kb/how-do-i-use-firefox-spell-checker
However, if there is not any dictionary installed yet (what was for me the case with a fresh installation - german language pack), there is no entry for spell checking in the context menu. And therefore the "Language" submenu to install dictionaries is missing as well. You have to manually search and navigate to the page with links to dictionaries to fix this. I head to search a few minutes to find the solution for this issue, as I was looking for the missing spell check context menu entry as I am used to on my other PC.
Proposal: Instead of removing any reference to spellchecking from the context menu, if there is no dictionary installed, show at least a shortcut entry to the dictionary installation page. Like "Install spell checker dictionary..." etc. Similar as in the "Language" submenu.
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