As it is now, show_hit should have a comment something like this:

# On Windows, selection highight is visible while the dialog is open.
# A 'hit' tag is used while the dialog is open (see #22179).
# The 'hit' tag should be deleted when this dialog is closed.
# The 'sel' tag keeps the text marked after closing.

However, there is a slight bug in show_hit behavior. For example, finding 'i' in "def i(): this list is 'is' # is not" finds all 6 'i's, one after the other, but only the 4 in identifier, plain text, builtin, and comment are visibly highlighted.  The 2 in the keyword and string are not.  The selection tag, however, is visible on the 'i' of "is" or "'is'"after the dialog is closed. Checking ColorDelegator, I do not see an obvious reason for why two tags are handled differently.

If this cannot be fixed, we should try the alternate fix of making the sel tag visible and dump the found tag. Otherwise, I think I like the heavier highlighting while the dialog is open.