[webkit-dev] Selection highlight painting ("gaps"?)

[Evan Martin]

When you select multiple lines of text in WebKit, the highlight paints
over whitespace on the right margin.
This is correct behavior for Mac, but not for Windows or Linux.

Epiphany (using WebKitGtk) does it Linux style, but my best efforts to
trace through the code have found no ifdefs related to platforms that
might make this happen.  I asked on various IRC channels and nobody
knew how it worked.

It seems these extra margins in the code are called "gaps" -- if I
make RenderBlock::getHorizontalSelectionGapInfo always return false,
the selections sorta behave as they do in Epiphany.  But none of this
code seems to be controlled by flags.  Does anyone know how it works?
I'm surely just missing a setting somewhere, but I have no idea how to
find it...