Provide an Executor implementation that runs submitted tasks on the JavaFX thread as an easily accessible static somewhere (perhaps Platform.getUpdateExecutor()).

It would look like:

  private final Executor updateExecutor = new Executor() {
    @Override
    public void execute(Runnable command) {
      Platform.runLater(command);
    }
  };

This makes it easier to use the concurrency API to handle background tasks which eventually need to do a small UI update, especially with for example the new Java 8 CompletableFuture that allows for multiple tasks to be chained and combined after which a UI update takes place. Here's an example (with only limited Lambda's, although the whole thing could be written as a one-liner):

   /*
    * Based on Task duration, select an Executor, then load an Image, then update the property with the Image.
    */

    CompletableFuture<Executor> futureExecutor = CompletableFuture.supplyAsync(() -> imageHandle.isFastSource() ? FAST_EXECUTOR : SLOW_EXECUTOR, FAST_EXECUTOR);
    CompletableFuture<Image> futureImage = futureExecutor.thenCompose(new Function<Executor, CompletionStage<Image>>() {
      @Override
      public CompletionStage<Image> apply(Executor executor) {
        return CompletableFuture.supplyAsync(() -> getImage(imageHandle), executor);
      }
    });
    
    CompletableFuture<Void> future = futureImage.thenAcceptAsync(image -> {
      property.set(image); // Must be on JavaFX UI thread
    }, new Executor() {
      @Override
      public void execute(Runnable command) {
        Platform.runLater(command);
      }
    });

The last part would be nice to write as:

    CompletableFuture<Void> future = futureImage.thenAcceptAsync(image -> {
      property.set(image); // Must be on JavaFX UI thread
    }, Platform.UPDATE_EXECUTOR);

This is only a minor request, and any kind of utility class can easily provide this executor, but I thought it might be good to have it as part of the platform.