ADDITIONAL SYSTEM INFORMATION :
Windows 10. Java 15.

A DESCRIPTION OF THE PROBLEM :
If I set TabPane to be reorderable, and start dragging a Tab and move the mouse violently to the left and right for some time (without releasing the mouse), the mouse x-offset will change.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a TabPane.
2. Add some tabs.
3. Start dragging one tab.
4. Move the mouse to the right and to the left for some time (quite rapidly)
5. You will notice that the X-offset "goes off" when doing this.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The mouse X-offset should stay where it was when the drag started.
ACTUAL -
The mouse X-offset changes.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class Test extends Application {

    @Override
    public void start(Stage primaryStage) {
        TabPane tabPane = new TabPane();
        tabPane.setTabDragPolicy(TabPane.TabDragPolicy.REORDER);

        tabPane.getTabs().add(new Tab("First"));
        tabPane.getTabs().add(new Tab("Second"));
        tabPane.getTabs().add(new Tab("Third"));
        tabPane.getTabs().add(new Tab("Fourth"));
        tabPane.getTabs().add(new Tab("Fifth"));

        StackPane root = new StackPane();
        root.getChildren().add(tabPane);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("TabPane bug");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    public static void main(String[] args) {
        launch(args);
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
None that I know of.

FREQUENCY : always