Title and tick formater ignored with graphics_array

[Andy Howell]

I'm trying to make graphics array with plots containing tick marks and a titles. 

When displayed individually, a.show(), b.show(), they display correctly. In a graphics_array however, the first graph looses these attributes (b).

f=4*sin(3*x)

b=plot(f,0,pi/3,ticks=pi/6,tick_formatter=pi, title="$4 sin(3\\theta)$")

b+=plot(f,pi/3, 2*pi/3,ticks=pi/6,tick_formatter=pi,color='red')

b+=plot(f,2*pi/3,pi, ticks=pi/6,tick_formatter=pi,color='green')

a=polar_plot(f,0,pi/3, title="Polar plot of $r=4 sin(3\\theta)$")

a+=polar_plot(f,pi/3,2*pi/3, color='red')

a+=polar_plot(f,2*pi/3,pi, color='green')

ga=graphics_array((b,a))

b.show()

a.show()

ga.show()

Also, I'd like to have an over-all title for the two graphs. Is there a way to do that?

Thanks,

Andy