ions to set up a mock plot with a data loading indicator if no data is specified.</div></div><div class=CToolTip id="tt334"><div class=CProperty><blockquote><table border=0 cellspacing=0 cellpadding=0 class=Prototype><tr><td>this.numberColumns = null</td></tr></table></blockquote>Maximum number of columns in the legend. </div></div><div class=CToolTip id="tt335"><div class=CProperty><blockquote><table border=0 cellspacing=0 cellpadding=0 class=Prototype><tr><td>this.numberColumns = null</td></tr></table></b