How to change linestyle of 2d vector field plots

edit

Look at the output below. You can see that it is possible to change the arrow style but not the linewidths.

sage: p = plot_vector_field((x, y), (x, -2, 2), (y, -2, 2), headlength=10, headwidth=10)
sage: p._objects
[PlotField defined by a 20 x 20 vector grid]
sage: P = p._objects[0]
sage: P._allowed_options()
{'color': 'The color of the arrows',
 'headaxislength': 'head length at shaft intersection, default is 4.5',
 'headlength': 'head length as multiple of shaft width, default is 5',
 'headwidth': 'Head width as multiple of shaft width, default is 3',
 'pivot': 'Where the arrow should be placed in relation to the point (tail, middle, tip)',
 'plot_points': 'How many points to use for plotting precision',
 'zorder': 'The layer level in which to draw'}

I must agree that the documentation of vector field is pretty poor. And the function definitely needs to add the functionality for linewidth, and possible other things. The plot_vector_field calls matplotlib's quiver function which has support for linewidth.

I just opened ticket 15724 and ticket 15725 to address these issues.