no adding a new property wont work.
what this is is css (default styling of webbrowssers (which perspective uses))
(well and svg as this is a svg specific style)
using either the stylesheet.css Style Classes - Ignition User Manual 8.1 - Ignition Documentation
or injection it in a styleClass by wrapping it in }{
(pay attention to the "psc-"InjectChartSize and the styleclass name for both methodes)
injection adds it to the dropdown while the stylesheet does not, but you can still type it in the classes manualy
