Can't edit the wiki and I have a change to make.
I noticed on the macro page that the value for “. matches newline” in the Regexp section is not documented. I believe it should be 1024.
I think this is a more direct link to what you are referring to.
I also think that you are correct, although probably a lot of Regular expression search mode users ignore the . matches newline checkbox and use instead
(?-s)at the start of their regular expression. Doing this makes unnecessary the need to know the 1024 mask value for the lParam of the 1702 message.
(?s)at the start of Find what means effectively . matches newline checkbox ticked
(?-s)at the start of Find what means effectively . matches newline checkbox cleared
. matches newline checkbox ticked means the 1024 mask value is used
. matches newline checkbox cleared means the 1024 mask value is not used