pixel of space in between lines in DrRacket.
This change is based on Matthew's experience having a look
at the font setup on the three platforms.
He writes:
> * Mac OS X: the convention seems to be to add space between lines.
> TextEdit, for example, looks like DrRacket: the maze has spaces.
>
> (I can't find a font that makes the maze look right, actually, even
> if I adjust the line spacing.)
>
> * Windows: the convention seems to be that space is built into the
> font. DrRacket (and SirMail) draw lines more sparsely than Notepad.
>
> Perhaps consistent with the differing conventions, the height of
> "Courier New" at 11-pixel size is 14 on Windows, 13 on Mac OS X.
>
> * Unix: the convention seems to be to add space. DrRacket looks like
> the default Terminal and Text Editor programs on Ubuntu.
>
> The maze nevertheless looks right everywhere, because the glyphs
> extend an extra pixel above the declared bounding box!
before the plain text-mode keymap.
Add a doubleleftclick binding to the scheme mode keymap so that
we can have sexp-sensitive double clicking in the drracket editor
line terminators when:
a) running under windows, and
b) the file on the disk (when DrRacket first opens it)
contains all CRLF line endings.
In all other situations, the file is saved with LF terminators.
Before this commit, DrRacket would always use the platform-specific
convention, regardless of the original content of the file.
closes PR 12242
This is a backwards incompatible change; there is a more complex change
that just stubs this stuff out that may be better that we may need
isntead of this commit.
