GWT Designer does not allow me to add custom component.

[rmehlinger]

So, I developed a simple custom component consisting of a panel, two
buttons, a text field, and a text area. I want to be able to embed
this component in my main window. However, when I attempt to add the
component into the main window of my program using the GWT palette, I
receive the error message shown below. In addition, as I hover the
mouse, a small hovertext box appears reading "Exception during live
image creation. See error log for details." I have a copy of the
zipped report file if there is any place that I can post it, as well:

Internal Error
GWT Designer encountered unexpected internal error.

This could be caused by a GWT Designer bug or by a misconfiguration
issue, conflict, partial update, etc.

Stack trace:
java.lang.NullPointerException
at
org.eclipse.wb.internal.swing.java6.model.SwingVisualMapper.getComponentPreferredSize(SwingVisualMapper.java:
85)
at
org.netbeans.modules.form.layoutdesign.LayoutDesigner.endMoving(LayoutDesigner.java:
596)
at
org.eclipse.wb.internal.layout.group.model.GroupLayoutSupport.command_create(GroupLayoutSupport.java:
276)
at
org.eclipse.wb.internal.layout.group.gef.GroupLayoutEditPolicy2$4.executeEdit(GroupLayoutEditPolicy2.java:
510)
at org.eclipse.wb.core.gef.command.EditCommand$1.run(EditCommand.java:
52)
at
org.eclipse.wb.internal.core.utils.execution.ExecutionUtils.run(ExecutionUtils.java:
318)
at
org.eclipse.wb.core.gef.command.EditCommand.execute(EditCommand.java:
50)
at
org.eclipse.wb.internal.gef.core.EditDomain.executeCommand(EditDomain.java:
59)
at org.eclipse.wb.gef.core.tools.Tool.executeCommand(Tool.java:209)
at
org.eclipse.wb.gef.core.tools.AbstractCreationTool.handleButtonUp(AbstractCreationTool.java:
62)
at org.eclipse.wb.gef.core.tools.Tool.mouseUp(Tool.java:395)
at
org.eclipse.wb.internal.gef.core.EditDomain.mouseUp(EditDomain.java:
255)
at
org.eclipse.wb.internal.gef.graphical.EditEventManager.mouseUp(EditEventManager.java:
149)
at sun.reflect.GeneratedMethodAccessor111.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.eclipse.wb.internal.draw2d.EventManager
$8.invoke(EventManager.java:325)
at $Proxy5.mouseUp(Unknown Source)
at
org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:
213)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:
4066)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3657)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:
2640)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
at
org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:
332)
at
org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:
664)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:
149)
at
org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:
115)
at
org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:
196)
at
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:
110)
at
org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:
79)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:
369)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:
179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:620)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:575)
at org.eclipse.equinox.launcher.Main.run(Main.java:1408)

The code for my custom component is:
<code>package com.charybdis.gui;

import javax.swing.JPanel;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JTextArea;
import javax.swing.JTextPane;
import java.awt.Font;
import javax.swing.JButton;
import javax.swing.border.LineBorder;
import java.awt.Color;

public class AddableSection extends JPanel {
/**
* Create the panel.
*/
public AddableSection()
{
super();
initialize();
}

private void initialize()
{
setBorder(new LineBorder(null, 1, true));

JTextArea textArea = new JTextArea();
textArea.setBorder(new LineBorder(new Color(0, 0, 0)));
textArea.setRows(10);

JButton button = new JButton("- Section");
button.setEnabled(false);

JButton button_1 = new JButton("+ Section");

JTextPane textPane = new JTextPane();
textPane.setBorder(new LineBorder(new Color(0, 0, 0)));
textPane.setText("Section Title");
textPane.setFont(new Font("Tahoma", Font.PLAIN, 16));
GroupLayout groupLayout = new GroupLayout(this);
groupLayout.setHorizontalGroup(
groupLayout.createParallelGroup(Alignment.LEADING)
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
.addComponent(textArea, GroupLayout.DEFAULT_SIZE, 478,
Short.MAX_VALUE)
.addGroup(Alignment.TRAILING,
groupLayout.createSequentialGroup()
.addComponent(textPane, GroupLayout.PREFERRED_SIZE, 286,
GroupLayout.PREFERRED_SIZE)
.addGap(18)
.addComponent(button_1, GroupLayout.PREFERRED_SIZE, 79,
GroupLayout.PREFERRED_SIZE)
.addGap(18)
.addComponent(button, GroupLayout.PREFERRED_SIZE, 75,
GroupLayout.PREFERRED_SIZE)))
.addContainerGap())
);
groupLayout.setVerticalGroup(
groupLayout.createParallelGroup(Alignment.LEADING)
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
.addComponent(button, GroupLayout.PREFERRED_SIZE, 26,
GroupLayout.PREFERRED_SIZE)
.addComponent(button_1))
.addComponent(textPane, GroupLayout.PREFERRED_SIZE, 22,
GroupLayout.PREFERRED_SIZE))
.addGap(11)
.addComponent(textArea, GroupLayout.DEFAULT_SIZE, 198,
Short.MAX_VALUE)
.addContainerGap())
);
setLayout(groupLayout);
}
}</code>

[Konstantin Scheglov]

1. This is not GWT Designer error, this is Swing Designer error, which is part of Eclipse.org and should be handler there.

2. Newsgroup is bad place for reporting errors like this. Create error report, as this is suggested by error page, and open Bugzilla bug and attach this error report.