@brolny
I won't be doing anything with fonts, alas

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For the word column width problem a simple resizing of the SpellcheckEditor window should suffice. For the problem with the width of "Change Selected Word To" box I will try to implement ToolTip (when you place your mouse on the object a text in a box will appear): it's not perfect but will help some, I think - see picture.
I would like to have a sample of your book, just a page with this long word would be enough. What language is this?