I didn't have to manually install one previously, Code::Blocks automatically selected or came with it. When I launch C::B 17.12, the Editor options confirm that it is using the dictionary that it came with at share\codeblocks\SpellChecker. Included in this folder is a file called "en_US.dic". I guess I'll have this nightly use that dictionary, if you believe that will work.
A bigger problem though is that this nightly build fails assertion and then crashes on launch if it is started during a Remote Desktop session. A C::B session I had already opened crashed immediately after I remote desktopped into the computer. This is a show stopper for me and I'll have to downgrade to 17.12. I hadn't used any of the nightlies since that release, so I don't know which other nightlies may be similarly affected. The assert message is as follows:
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A debugging check in this application has failed.
../../src/msw/bitmap.cpp(1346): assert "" Assert failure"" failed in GetRawData(): incorrect bitmap type in wxBitmap::GetRawData()
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If I click continue instead of stop, this alert dialog message is diplayed:
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A debugging check in this application has failed.
../../src/msw/bitmap.cpp(272): assert "!m_dib" failed in Free(): forgot to call wxBitmap::UngetRawData()!
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Continuing to click Continue just repeatedly alternates between these two messages, possibly indefinitely, until stop is clicked and the program is allowed to crash.