Simos, I did not exactly follow the way you've described, I used the way I usually add to get spellchecking support for various languages. Anyway, I was able to reproduce this bug with Greek. Here's what was done:
a. I don't install full support for all the languages, since I'm quite comfortable with Russian as a system language. Instead, I install aspell packages for corresponding languages, since GNOME (and Evolution as a part of it) relies on aspell to do spellchecks. So I did "sudo aptitude install aspell-el" for Greek, restarted Evolution, opened a new message, activated Greek spellchecking in Edit -> Current languages menu, and then pasted the example phrase you've provided into the editor. The last word appeared underlined as a mistype.
1. F7 did not found any misspelled words, despite the fact that last word was marked as such.
2. Secondary click on the underlined word did not bring in any suggestions at all.
b. After that, I have typed in a phrase in Russian, "проверка русской арфографии". This phrase contains a mistype in last word (should read "орфографии"), and this word was underlined as mistyped. After that, I tried to explore the bug again.
1. F7 ignores Greek mistype, and only shows Russian one (with valid suggestions).
2. Secondary click on underlined words brings no suggestions, neither for Greek nor for Russian mistypes.
c. Then, I turned Greek spellchecking off in menu, leaving other languages on. After that, all words in Greek phrase were underlined (as expected, since Greek dictionary was no longer active), as well as the last (actually mistyped) word in Russian phrase. In this situation:
1. F7 ignores Greek words and shows Russian mistyped word with valid suggestions.
2. Secondary click on underlined words brings no suggestions, not even for Russian.
d. Then, I created a new message, kept Greek spellchecking disabled, and typed in the Russian example (no Greek in this letter).
1. F7 works as intended.
2. Secondary click works as intended.
e. Then, I pasted the Greek example into the second message. Secondary click got broken, repeating situation [c].
f. After a few more tests, Russian was stably producing situation [a] (both F7 and secondary click don't work) with all the mistypes I have previously used. Removing Greek support totally (sudo aptitude remove aspell-el) didn't help fix Russian back again: the examples I have used when Greek was installed produce situation [a], while some other Russian mistypes work correctly. All other languages I use (Swedish, German, English, Esperanto, Ukrainian and Lithuanian) work correctly.
So here is my conclusion: Greek spellchecking in Evolution is buggy and effectively breaks other languages as well. Right now, I even have no clue how to repair Russian back again...
Simos, I did not exactly follow the way you've described, I used the way I usually add to get spellchecking support for various languages. Anyway, I was able to reproduce this bug with Greek. Here's what was done:
a. I don't install full support for all the languages, since I'm quite comfortable with Russian as a system language. Instead, I install aspell packages for corresponding languages, since GNOME (and Evolution as a part of it) relies on aspell to do spellchecks. So I did "sudo aptitude install aspell-el" for Greek, restarted Evolution, opened a new message, activated Greek spellchecking in Edit -> Current languages menu, and then pasted the example phrase you've provided into the editor. The last word appeared underlined as a mistype.
1. F7 did not found any misspelled words, despite the fact that last word was marked as such.
2. Secondary click on the underlined word did not bring in any suggestions at all.
b. After that, I have typed in a phrase in Russian, "проверка русской арфографии". This phrase contains a mistype in last word (should read "орфографии"), and this word was underlined as mistyped. After that, I tried to explore the bug again.
1. F7 ignores Greek mistype, and only shows Russian one (with valid suggestions).
2. Secondary click on underlined words brings no suggestions, neither for Greek nor for Russian mistypes.
c. Then, I turned Greek spellchecking off in menu, leaving other languages on. After that, all words in Greek phrase were underlined (as expected, since Greek dictionary was no longer active), as well as the last (actually mistyped) word in Russian phrase. In this situation:
1. F7 ignores Greek words and shows Russian mistyped word with valid suggestions.
2. Secondary click on underlined words brings no suggestions, not even for Russian.
d. Then, I created a new message, kept Greek spellchecking disabled, and typed in the Russian example (no Greek in this letter).
1. F7 works as intended.
2. Secondary click works as intended.
e. Then, I pasted the Greek example into the second message. Secondary click got broken, repeating situation [c].
f. After a few more tests, Russian was stably producing situation [a] (both F7 and secondary click don't work) with all the mistypes I have previously used. Removing Greek support totally (sudo aptitude remove aspell-el) didn't help fix Russian back again: the examples I have used when Greek was installed produce situation [a], while some other Russian mistypes work correctly. All other languages I use (Swedish, German, English, Esperanto, Ukrainian and Lithuanian) work correctly.
So here is my conclusion: Greek spellchecking in Evolution is buggy and effectively breaks other languages as well. Right now, I even have no clue how to repair Russian back again...