ADDITIONAL SYSTEM INFORMATION :
OS: macOS 10.14.4
JDK: openjdk-12.0.2

A DESCRIPTION OF THE PROBLEM :
It is possible to change the hover state of the buttons inside a dialog without placing the mouse over the button but by mere resizing of the dialog.

I first run into this on openjdk-11.0.1. Could reproduce it on 12.0.2.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Open a dialog and resize its bottom right corner until the rightmost button is located at the very position, where the mouse was pressed to start the resizing.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The button state is not affected by the resizing.
ACTUAL -
The button changes its state to hovered when through resizing of the dialog it is positioned such that it contains the point where the last mouse press had happened.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceDialog;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
import org.jetbrains.annotations.NotNull;

public class Debugging_hover_on_resize extends Application {

  public static void main(String[] args) {
    launch(args);
  }

  @Override
  public void start(final Stage primaryStage) throws Exception {
    final BorderPane root = new BorderPane();

    final Button button = new Button("Click me");
    button.setOnAction(event -> {
// showAlert(primaryStage);
// showChoiceDialog(primaryStage);
      showStageBasedCustomDialog(primaryStage);
    });

    root.setCenter(button);

    primaryStage.setScene(new Scene(root, 600, 400));
    primaryStage.show();
  }

  private void showAlert(final Stage owner) {
    final Alert alert = new Alert(Alert.AlertType.INFORMATION);
    alert.initOwner(owner);
    alert.setResizable(true);
    alert.showAndWait();
  }

  private void showChoiceDialog(final Stage owner) {
    final ChoiceDialog<String> choiceDialog = new ChoiceDialog<>("OK", "Cancel");
    choiceDialog.initOwner(owner);
    choiceDialog.setResizable(true);
    choiceDialog.showAndWait();
  }

  // this pseudo-dialog makes the problem most obvious with green buttons on hover
  private void showStageBasedCustomDialog(final Stage owner) {
    final Stage stage = new Stage();
    stage.initOwner(owner);

    final Pane buttonPane = new HBox(12);
    final Button button1 = new Button("OK");
    button1.setOnAction(event -> System.out.println("OK"));
    button1.hoverProperty().addListener(createOnHoverListener(button1));

    final Button button2 = new Button("Cancel");
    button2.setOnAction(event -> System.out.println("Cancel"));
    button2.hoverProperty().addListener(createOnHoverListener(button2));

    buttonPane.getChildren().addAll(button1, button2);

    final AnchorPane root = new AnchorPane();
    root.getChildren().addAll(buttonPane);
    AnchorPane.setBottomAnchor(buttonPane, 12.0);
    AnchorPane.setRightAnchor(buttonPane, 12.0);

    stage.setScene(new Scene(root, 400, 300));
    stage.show();
  }

  @NotNull
  private ChangeListener<Boolean> createOnHoverListener(final Button button) {
    return (observable, wasHovered, isHovered) -> {
      final String style = isHovered ? "-fx-background-color: green;" : "";
      button.setStyle(style);
    };
  }
}
---------- END SOURCE ----------

FREQUENCY : always