JavaFX Layout issue within hbox - javafx

Question

I want to add an statusbar to my application (the root pane is a vbox and the statusbar is a hbox with a fix height). On this statusbar I have a label with something like "2 processes running". As soon as the mouse hoovers this label, I want to add a Pane above this label with some details about the processes (like IntelliJ or Eclipse).
My problem in the moment is how to create this pane and position this pane above the label.
I create a simple example of my problem
The green area is a StackPane on the root VBox with VGow = Always. The red area is the Hbox with a fix height of 30 pixel. Then I added the yellow VBox the the HBox and put the minHeight to 300.
The problem is, that the yellow area should be above the red area (over the green area) and not outside the window.
What is the best way to achive something like that?
The only way I figured out was using a negative top margin amount (- max/min height). But then the window gets stretched because the yellow pane (or the green bordered pane is not on top of the other elements). The red crossed area shouldn't be there. The green boxed area should be above the other content. Probably I can't use a vbox as my root element?
Update 1
Here is an example - strange thing is, that it is working in this standalone example. But is that the way I should do something like that?
VBox rootBox = new VBox();
rootBox.setMaxHeight(500);
rootBox.setStyle("-fx-background-color: lightgreen");
StackPane contentPane = new StackPane();
contentPane.getChildren().add(new Button("Dont click me"));
contentPane.setStyle("-fx-background-color: lightblue");
VBox.setVgrow(contentPane, Priority.ALWAYS);
HBox statusbar = new HBox();
statusbar.setMinHeight(30);
statusbar.setMaxHeight(30);
statusbar.setStyle("-fx-background-color: red");
VBox processIndicatorBox = new VBox();
processIndicatorBox.setMinHeight(30);
processIndicatorBox.setMaxHeight(30);
HBox.setMargin(processIndicatorBox, new Insets(-300, 0, 0, 0));
StackPane processListPane = new StackPane();
processListPane.setStyle("-fx-background-color: yellow");
processListPane.setMinHeight(300);
processListPane.setMaxHeight(300);
processListPane.setMinWidth(150);
processListPane.setMaxWidth(150);
processListPane.setVisible(false);
Label label = new Label("Show processes");
label.setOnMouseEntered(mouseEvent -> processListPane.setVisible(true));
label.setOnMouseExited(mouseEvent -> processListPane.setVisible(false));
processIndicatorBox.getChildren().addAll(processListPane, label);
statusbar.getChildren().add(processIndicatorBox);
rootBox.getChildren().addAll(contentPane, statusbar);
Scene scene = new Scene(rootBox, 600, 500);
primaryStage.setScene(scene);
primaryStage.show();
Many greetings
Hauke

Answer 1

Did you consider using GridPane? ( https://docs.oracle.com/javase/8/javafx/api/javafx/scene/layout/GridPane.html ). Gives you more control to layout elements with different sizes. VBox and HBox are from my experience good when all elements have similar sizes.
Here a pseudo-pseudo code
GridPane grid = new GridPane();
Pane greenBox = new Pane(); //your green box
Pane redBox = new Pane(); //your red box
Pane yellowBox = new Pane(); //your yellow box
// add the panes to the grid pane and define where they are
grid.add(greenBox, 0, 0); set the green box in column 0 and row 0
grid.add(redBox, 0, 1); set the red box in column 0 and row 1
grid.add(yellowBox, 1, 1); set the yellowbox in column 1 and row 1
// size of the boxes
GridPane.setColumnSpan(greenBox,2); //The green box should span over 2 columns
GridPane.setRowSpan(yellowBox,2); //The red box should span over 2 rows
The boxes are now only empty panes, which will have a minimum size without content. Replace the Pane() boxes with the content you want to put in or put the content in the Pane() objects.