Given the issues I raised and Raymond's rejection of this, his first suggested option, on the PR, in favor of his second suggested option, #33046, I agree, at least for now.

The use case for whitespace tagging would be if someone wants to selectively delete trailing whitespace.  However, python/cpython rejects any trailing whitespace for all of .py, .c, and .rst files.  So this must be exceedingly rare and is not something that IDLE must facilitate.