Now that I've got my chart running transparent, how can I get the rectangle (top/left/bottom/right) coordinates of the actual chart (not labels and padding) being displayed on the screen? I tried the plotPadding getters, but that doesn't seem to be it -- they're always zero.
You want getViewportRect:
This will return to you the rectangle that represents the inner coordinates of the plot area within the chart component.
Hope this helps!