In QtC, when you place the cursor on some function, you can chose from the context menu item [Find Usages] which... finds usages of this function! So, instead of looking up "HTMLSpellCheck.cpp", as suggested, I applied [Find Usages] on class "SpellCheck". I know, I know... but, in my wanderings, I've encountered the "HtmlSpellcheck" class already (I don't write everything here, it's boring enough as it is

): it is a scary one and I'm not up to it yet :|.
So [Find Usages] "Spellcheck":
69 matches found:
SpellCheckWidget.cpp (12)
SpellCheckEditor.cpp (10)
MainWindow.cpp (4)
HtmlSpellCheck.ccp (2) ha!
SpellCheck.ccp (28) I was there!
SpellCheck.h (5) ...and here too!
CodeViewEditor.cpp (8)
Eventually will have to visit all those palaces... but let's look at SpellCheckEditor first...
tbc...?