Generating axis tick annotation that occupies 2 lines

Question

I have a time series I an plotting with jqPlot where I am using a custom tick renderer for the X axis values. However I want to display text shown at each tick position as 2 lines, stacked one above the other. I've tried rendering the string with sprintf and using "\n" but it seems to have no effect - can this be done?

I notice in the demos at http://www.jqplot.com/tests/barRendererTests.php there is a Y axis tick annotation string that occupies 2 lines. Presumably this is because the string was too long for some rectangle specified somewhere - maybe these is a similar technique (a bounding rectangle) for the X ticks?

TIA