\pgfarrowsdeclare{latex}{latex}
{
\pgfutil@tempdima=0.28pt%
\pgfutil@tempdimb=\pgflinewidth%
\ifdim\pgfinnerlinewidth>0pt%
\pgfmathsetlength\pgfutil@tempdimb{.6\pgflinewidth-.4*\pgfinnerlinewidth}%
\fi%
\advance\pgfutil@tempdima by.3\pgfutil@tempdimb%
\pgfarrowsleftextend{+-1\pgfutil@tempdima}
\pgfarrowsrightextend{+9\pgfutil@tempdima}
}
{
\pgfutil@tempdima=0.28pt%
\pgfutil@tempdimb=\pgflinewidth%
\ifdim\pgfinnerlinewidth>0pt%
\pgfmathsetlength\pgfutil@tempdimb{.6\pgflinewidth-.4*\pgfinnerlinewidth}%