I see strange rendering of text on some web pages.

Sometimes black text shows up magenta.
Once this happens if I scroll the page down, the text will change from magenta back to black, but it will leave a very faint imprint behind like when type comes off a piece of newspaper and sticks to something.
I attached a couple of screenshots. You have to look closely at the shadow text screenshot because the effect is a bit subtle - the purple is easy to spot though ;-)

An example of the strange rendering is http://andrew-hoyer.com/experiments/cloth/ - this page displays a canvas with a cloth simulation and additional text. The text displays as described above and the lines in the simulation don't display. The page used to display fine, not sure what broke it. I might try downgrading my JavaFX version to see if that fixes it.

Test App
import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.web.WebView; import javafx.stage.Stage;
public class WebViewCloth extends Application {
  public static void main(String[] args) throws Exception { launch(args); }
  public void start(final Stage stage) throws Exception {
    WebView webView = new WebView(); webView.getEngine().load("http://andrew-hoyer.com/experiments/cloth/");
    stage.setScene(new Scene(webView)); stage.show();
  }
}