Scenario (see attached Java file):
There are two StackPanes (pane1 & pane2) being displayed in a SplitPane (splitPane). The SplitPane's divider position is set to .3 before the Stage is shown (environment A). The second StackPane (pane2) contains a Button which sets the SplitPane's divider position to .3 when clicked (environment B). Notice that both inputs are the same (.3). Then, the SplitPane is put in a Scene, which is put on a Stage, which is shown.

Issue #1:
Ceteris paribus and since the inputs are the same (.3), the expected behaviour would be that the divider position is the very same for both environments. Yet, the onscreen outcomes are different.

Issue #2:
Only in environment B the divider is set correctly (based on visual judgement), while in environment A other measures appear to influence the calculations.

This bug has been reported before and marked "Cannot Reproduce". With this example it is reproducable.
http://javafx-jira.kenai.com/browse/RT-17229

Additional Observation:
- The environment A outcome is influenced by setResizableWithParent(Node node, java.lang.Boolean value).

Proposed Fixes:
- setDividerPositions(double... positions) and the like lack documentation of different behaviours depending on window resizing.
- Provide methods or fix existing methods in order to provide environment B functionality (i.e., correct placement) for environment A.

Attached Java file:
I would love to do that and I've done it before, but I cannot find the command to do so. Therefore, this is my test case in plain code:


    StackPane pane1 = new StackPane();
    StackPane pane2 = new StackPane();

    final SplitPane splitPane = SplitPaneBuilder.create()
            .items(pane1, pane2)
            // Environment A
            .dividerPositions(new double[] {.3}) // splitPane.setDividerPosition(s)(...), etc. yield same result
            .orientation(Orientation.HORIZONTAL)
            .build();

    // The following line influences environment A outcome, though it does not fix the issue
    SplitPane.setResizableWithParent(pane1, false);

    pane2.getChildren().add(ButtonBuilder.create()
            .text("Divider Position")
            .onAction(new EventHandler<ActionEvent>() {
                @Override
                public void handle(ActionEvent event) {
                    // Environment B
                    splitPane.setDividerPositions(.3);
                }
            })
            .build());

    Scene primaryScene = SceneBuilder.create()
            .root(splitPane)
            .build();

    primaryStage.setScene(primaryScene);
    primaryStage.setTitle("Name");
    primaryStage.setWidth(500);
    primaryStage.setHeight(500);
    primaryStage.show();