Spellchecker should be able to handle multiple words

[kelson42]

For the moment we can only request the spellchecker for one word. But actually users type many words, so we should consider to support many words (to be able to go over the special dictionary case of DWDS)

[kelson42]

@veloman-yunkan I think this feature request will requires extended discussion. At this stage I don´t see how this could work well... Do you?