Patch to highlight squares themselves (not borders or arrows) for last move and premove

[Nathan Teodósio]

If the line gap is zero the only way to see last- and premoves is to enable
the arrows option.

The attached patch will color the "from" and "to" squares interior when the
line gap is zero, with the resulting behavior being analogous to Lichess'
and Chess.com's.

Are you interested in the patch? Do you think it should be added as a separate
option instead? Or maybe reworked into say a single highligh option with
a combobox for {square interior, arrow, border}?

Cheers,
Nathan Teodosio

highlight-square-interior.patch
Description: Text Data