Normally, draw_heatmap is called from within heatmap.n2 (if argument
plot is TRUE which is the default) but if that is not desired, e.g., for zooming, it can be called
separately.
draw_heatmap(dl, set.oma = TRUE, ...)(list). The "display list": A list with all parameters needed for plotting the heatmap.
(logical). Should the outer margins be set to optimized values? Defaults to TRUE.
(list). Additional parameters passed to plot.
Invisibly returns a list with graphical parameters. But mainly the function is called for its side-effect of generating a plot.