With printing, rendering methods can be called on any thread. Sometimes they need to know whether they run on Render thread or not, e.g. to access accelerated textures safely. A new method similar to Toolkit.isFxUserThread() would help.
JDK-8087696Reimplement PrismInvoker.runOnRenderThread() once RT-28481 is fixed
JDK-8101135Webview and HTMLEditor should support printing their content