size 400,400
xrange -10,10
yrange -10,10
grid 1,1,grey
rotationcenter 0,0
# slider is active for all following objects until 'killslider'
slider -10,10,300,40,angle degree,Rotate
drag xy
# after dragging the object must be clicked to re-activate the slider
linewidth 4
arrow 0,0,6,0,9,blue

# reset rotation center to the first (x,y) of the next object/arrow...
killrotate
drag xy
# after dragging the object must be clicked to re-activate the slider
arrow 0,0,6,1,9,red
