Allow text labels inside the plot?

[esalvolucas]

In regular IDL tplot, I think we can make text labels appear at an arbitrary x-y coordinate. Is that possible in bokeh/pyqtgraph?

If so, feel free to add a dictionary object to TVar that contains a list of labels that will be plotted inside the plot. Then, you can add a new function to all those TVarFigures called _add_text() that looks through that dictionary and writes things in the plots.