TornadoFx Undecorated window goes fullscreen when restored from task bar

I think this is a general problem in JavaFX (I mean not specific with TornadoFX).

The root cause for this is because of setting the maximized property of stage to true. Not sure what JavaFX internally does, but when you open the window from task bar and if the maximized value is true, then it renders in full screen mode.

You can fix this in two ways.

Approach #1:

When the window is opened from task bar, the iconfied property will turn off, set the stage dimensions again to screen bounds if maximized is true.

primaryStage.iconifiedProperty().addListener((obs,old,iconified)->{
    if(!iconified && primaryStage.isMaximized()){
        primaryStage.setWidth(screenBounds.getWidth());
        primaryStage.setHeight(screenBounds.getHeight());
    }
});

Approach #2:

Don't rely on the maximized property of the Stage. I believe you need that property to toggle the window dimensions. So instead maintain a instance variable to handle that.

boolean maximized = false;
ma.setOnAction(e -> {
    if (maximized) {
        // Set stage to original bounds
        maximized = false;
        ma.setText("Ma");
    } else {
        // Set stage to screen bounds
        maximized = false;
        ma.setText("Re");
    }
});

A full working demo is below with both the approaches. You can decide which way to go based on your other requirments.

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Rectangle2D;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Screen;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class UndecoratedWindowFullScreenDemo extends Application {
    private double xOffset = 0.0;
    private double yOffset = 0.0;
    private Rectangle2D screenBounds = Screen.getPrimary().getVisualBounds();
    private Rectangle2D originalBounds = Rectangle2D.EMPTY;
    private boolean maximized = false;

    @Override
    public void start(Stage primaryStage) throws Exception {
        BorderPane root = new BorderPane();
        root.setStyle("-fx-background-color:pink;");
        Scene scene = new Scene(root, 600, 450);
        primaryStage.setScene(scene);

        Label label = new Label("Forums");
        Button mi = new Button("Mi");
        Button ma = new Button("Ma");
        Button x = new Button("X");
        HBox pane = new HBox(mi, ma, x);
        pane.setPadding(new Insets(3));
        pane.setSpacing(5);
        root.setCenter(label);
        root.setRight(pane);

        primaryStage.initStyle(StageStyle.UNDECORATED);
        primaryStage.setMinWidth(600);
        primaryStage.setMinHeight(450);
        primaryStage.setMaximized(false);
        primaryStage.show();

        root.setOnMousePressed(e -> {
            xOffset = primaryStage.getX() - e.getScreenX();
            yOffset = primaryStage.getY() - e.getScreenY();
        });
        root.setOnMouseDragged(e -> {
            primaryStage.setX(xOffset + e.getScreenX());
            primaryStage.setY(yOffset + e.getScreenY());
        });
        mi.setOnAction(e -> primaryStage.setIconified(true));

        /* Use this approach if you want to go with the Stage maximized property */
        // approach1(primaryStage, ma);

        /* Use this approach if you want to avoid Stage maximized property and maintain a instance variable */
        approach2(primaryStage, ma);
    }

    private void approach1(Stage primaryStage, Button ma) {
        primaryStage.iconifiedProperty().addListener((obs, old, iconified) -> {
            if (!iconified && primaryStage.isMaximized()) {
                primaryStage.setWidth(screenBounds.getWidth());
                primaryStage.setHeight(screenBounds.getHeight());
            }
        });

        ma.setOnAction(e -> {
            if (primaryStage.isMaximized()) {
                primaryStage.setX(originalBounds.getMinX());
                primaryStage.setY(originalBounds.getMinY());
                primaryStage.setWidth(originalBounds.getWidth());
                primaryStage.setHeight(originalBounds.getHeight());
                primaryStage.setMaximized(false);
                ma.setText("Ma");
            } else {
                originalBounds = new Rectangle2D(primaryStage.getX(), primaryStage.getY(), primaryStage.getWidth(), primaryStage.getHeight());
                primaryStage.setX(screenBounds.getMinX());
                primaryStage.setY(screenBounds.getMinY());
                primaryStage.setWidth(screenBounds.getWidth());
                primaryStage.setHeight(screenBounds.getHeight());
                primaryStage.setMaximized(true);
                ma.setText("Re");
            }
        });
    }

    private void approach2(Stage primaryStage, Button ma) {
        ma.setOnAction(e -> {
            if (maximized) {
                primaryStage.setX(originalBounds.getMinX());
                primaryStage.setY(originalBounds.getMinY());
                primaryStage.setWidth(originalBounds.getWidth());
                primaryStage.setHeight(originalBounds.getHeight());
                maximized = false;
                ma.setText("Ma");
            } else {
                originalBounds = new Rectangle2D(primaryStage.getX(), primaryStage.getY(), primaryStage.getWidth(), primaryStage.getHeight());
                primaryStage.setX(screenBounds.getMinX());
                primaryStage.setY(screenBounds.getMinY());
                primaryStage.setWidth(screenBounds.getWidth());
                primaryStage.setHeight(screenBounds.getHeight());
                maximized = true;
                ma.setText("Re");
            }
        });
    }
}