I am wondering why ProjectionPlot (and others) do not take all the keyword
arguments and pass them to PWViewerMPL and PlotWindow. For example,
currently there is no way to set buff_size at the creation of a plot. One
has to call .set_buff_size after the plot was created.
I am thinking about leaving only the arguments specific to ProjectionPlot
explicitly, and use **kwargs to pass all other arguments to PlotWindow. But
if there are reasons not to do this, please let me know.