I don't have a windows box handy; if I did I would try:

in gui-win32/screen.c change the calls to GetDeviceCaps to SystemParametersInfo with SPI_GETWORKAREA parameter. something like:

RECT ds; // size of work area in primary display
if( SystemParametersInfo(SPI_GETWORKAREA, 0, &ds, 0) ){
  dx = ds.right - ds.left;
  dy = ds.bottom - ds.top;
}

FYI:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms724947(v=vs.85).aspx

On Tue, Nov 3, 2015 at 7:51 AM, <a@9srv.net> wrote:
The Windows drawterm is pretty naive about screen
sizes: it doesn't take into account window size,
the stupid title bar, or multiple monitors. Inferno
has dealt with at least some of this. Does anyone
have a drawterm that deals with this better? Or has
anyone tried and run into issues?