为什么在我的TopComponent上消失了JavaFX内容？

试试这个：

Platform.setImplicitExit(false);

我们遇到同样的问题。基于以下线程，我们假设一旦面板不再可见，JavaFX 平台将自动退出，因为所有 JavaFX gui 元素都不再可见。

此假设基于以下信息：
https://forums.oracle.com/forums/thread.jspa?messageID=10287328 和
https://forums.oracle.com/forums/thread.jspa?threadID=2390971

在我们环境中的第一个尝试是在代码中的某个地方添加一个虚拟的JFXPanel，并将其留在那里，直到你的程序退出似乎工作。

第二次尝试你的代码也有效：

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package de.jeed.nbgan.accexplorer;

import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.geometry.Rectangle2D;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.ButtonBuilder;
import javafx.scene.paint.Color;
import javafx.stage.Modality;
import javafx.stage.Screen;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import org.netbeans.api.settings.ConvertAsProperties;
import org.openide.awt.ActionID;
import org.openide.awt.ActionReference;
import org.openide.windows.TopComponent;
import org.openide.util.NbBundle.Messages;

/**
 * Top component which displays something.
 */
@ConvertAsProperties(dtd = "-//de.jeed.nbgan.accexplorer//accex//EN",
autostore = false)
@TopComponent.Description(preferredID = "accexTopComponent",
//iconBase="SET/PATH/TO/ICON/HERE", 
persistenceType = TopComponent.PERSISTENCE_ALWAYS)
@TopComponent.Registration(mode = "explorer", openAtStartup = true)
@ActionID(category = "Window", id = "de.jeed.nbgan.accexplorer.accexTopComponent")
@ActionReference(path = "Menu/Window" /*
 * , position = 333
 */)
@TopComponent.OpenActionRegistration(displayName = "#CTL_accexAction",
preferredID = "accexTopComponent")
@Messages({
    "CTL_accexAction=accex",
    "CTL_accexTopComponent=Konten-Explorer",
    "HINT_accexTopComponent=Durchsuchen von Abteilungen und Konten"
})
public final class accexTopComponent extends TopComponent {

    static JFXPanel myFX;
    static JFXPanel myDummyFXtoKeepJavaFxRunning;

    public accexTopComponent() {
        initComponents();
        setName(Bundle.CTL_accexTopComponent());
        setToolTipText(Bundle.HINT_accexTopComponent());
        putClientProperty(TopComponent.PROP_CLOSING_DISABLED, Boolean.TRUE);
        myFX = new JFXPanel();
        myDummyFXtoKeepJavaFxRunning = new JFXPanel();
        Platform.runLater(new Runnable() {

            @Override
            public void run() {
                // Actual FX code that will be hidden/shown
                myFX.setScene(new Scene(ButtonBuilder.create().minHeight(40.0).minWidth(40.0).build()));

                // Workaround
                Stage dummyPopup = new Stage();
                dummyPopup.initModality(Modality.NONE);
                // set as utility so no iconification occurs
                dummyPopup.initStyle(StageStyle.UTILITY);
                // set opacity so the window cannot be seen
                dummyPopup.setOpacity(0d);
                // not necessary, but this will move the dummy stage off the screen
                final Screen screen = Screen.getPrimary();
                final Rectangle2D bounds = screen.getVisualBounds();
                dummyPopup.setX(bounds.getMaxX());
                dummyPopup.setY(bounds.getMaxY());
                // create/add a transparent scene
                final Group root = new Group();
                dummyPopup.setScene(new Scene(root, 1d, 1d, Color.TRANSPARENT));
                // show the dummy stage
                dummyPopup.show();

                // size back to scene size
                dummyPopup.sizeToScene();   

                // if you centered it before hiding
                //dummyPopup.centerOnScreen();      
            }
        });

        jPanel1.add(myFX);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();

        jPanel1.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.RAISED));
        jPanel1.setLayout(new java.awt.GridBagLayout());

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(54, 54, 54)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, 193, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(153, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(33, 33, 33)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, 193, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(74, Short.MAX_VALUE))
        );
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    private javax.swing.JPanel jPanel1;
    // End of variables declaration                   

    @Override
    public void componentOpened() {
        // TODO add custom code on component opening
    }

    @Override
    public void componentClosed() {
        // TODO add custom code on component closing
    }

    void writeProperties(java.util.Properties p) {
        // better to version settings since initial version as advocated at
        // http://wiki.apidesign.org/wiki/PropertyFiles
        p.setProperty("version", "1.0");
        // TODO store your settings
    }

    void readProperties(java.util.Properties p) {
        String version = p.getProperty("version");
        // TODO read your settings according to their version
    }
}