More generic version of code:
[x,y]=ginput(2); %start and endof arrow
AX=axis(gca); %can use this to get all the current axes
Xrange=AX(2)-AX(1);
Yrange=AX(4)-AX(3);
X=(x-AX(1))/Xrange +AX(1)/Xrange;
Y=(y-AX(3))/Yrange +AX(3)/Yrange;
annotation('textarrow', X, Y,'String' , 'LegendText','Fontsize',12);
