Get labeled entities from a VTK plot.
val = hplot.getlabels(type,mode)
val = hplot.getlabels;
This method returns the IDs of the labeled entities on a VTK plot.
TYPE specifies the type of entity for which to extract the labels -- 'node' (default) or 'element'.
MODE controls which display the labels will be extracted from -- 'undeformed' (default) or 'deformed'.
VAL is a vector of the entity IDs in the order in which they were picked.
>> val = hplot.getlabels('node');
>> val = hplot.getlables('elem','def');