RFR: 8367557: Extended stage seems to hang after drag and drop

[Michael Strauß]

On Wed, 10 Dec 2025 05:34:52 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> An extended stage seems to hang after a drag and drop operation. Note that in the attached reproducer, the application seems unresponsive until the mouse cursor leaves and re-enters the application window:
> 
> 
> import javafx.application.Application;
> import javafx.scene.Scene;
> import javafx.scene.control.Label;
> import javafx.scene.input.ClipboardContent;
> import javafx.scene.input.Dragboard;
> import javafx.scene.input.TransferMode;
> import javafx.scene.layout.BorderPane;
> import javafx.scene.layout.HBox;
> import javafx.scene.layout.HeaderBar;
> import javafx.stage.Stage;
> import javafx.stage.StageStyle;
> 
> public class DragDropTest extends Application {
> 
>     @Override
>     public void start(Stage primaryStage) {
> 
>         primaryStage.initStyle(StageStyle.EXTENDED);
> 
>         // Create drag source
>         Label dragSource = new Label("Drag me!");
>         dragSource.setStyle("-fx-background-color: lightblue; -fx-padding: 10px");
> 
>         // Create drop target
>         Label dropTarget = new Label("Drop here!");
>         dropTarget.setStyle("-fx-background-color: lightcoral; -fx-padding: 20px; -fx-min-width: 150px; -fx-min-height: 100px;");
> 
>         // Set up drag detection
>         dragSource.setOnDragDetected(event -> {
>             Dragboard dragboard = dragSource.startDragAndDrop(TransferMode.COPY);
>             ClipboardContent content = new ClipboardContent();
>             content.putString("Hello from drag source!");
>             dragboard.setContent(content);
>             event.consume();
>         });
> 
>         // Set up drag over
>         dropTarget.setOnDragOver(event -> {
>             if (event.getGestureSource() != dropTarget && event.getDragboard().hasString()) {
>                 event.acceptTransferModes(TransferMode.COPY);
>             }
>             event.consume();
>         });
> 
>         // Set up drag entered (visual feedback)
>         dropTarget.setOnDragEntered(event -> {
>             if (event.getGestureSource() != dropTarget && event.getDragboard().hasString()) {
>                 dropTarget.setStyle("-fx-background-color: lightgreen; -fx-padding: 20px; -fx-min-width: 150px; -fx-min-height: 100px;");
>             }
>             event.consume();
>         });
> 
>         // Set up drag exited (reset visual feedback)
>         dropTarget.setOnDragExited(event -> {
>             dropTarget.setStyle("-fx-background-color: lightcoral; -fx-padding: 20px; -fx-min-width: 150px; -fx-min-height: 100px;");
>             event.consume();
>         });
> 
>         // Set up drop
>         dropTarget.setOnD...

> Could this bug be related to [#1936 (comment)](https://github.com/openjdk/jfx/pull/1936#issuecomment-3720278382) ?

No, but I understand the reason for the other bug. Already working on a solution for it.

-------------

PR Comment: https://git.openjdk.org/jfx/pull/2003#issuecomment-3721261402