WindowBuilder barely works anymore (could be Forms related)

[jeffecom]

Hi,

I've used WB a lot in the past, but it seems to be barely functional now. Only the simplest of controls I created in previous version seem to display properly in the WB editor.

I made a simple test case to investigate:

1. Downloaded a fresh Eclipse 2025-12
2. Created an empty project (set to JDK21) and made a single class.
3. These are the Eclipse jars added.

4. Opened the class in WB designer and added a few controls. It's OK up until this point:

5. When I try to add a Composite to the body of the Section, the WB editor goes blank and that's it. Deleting the Composite doesn't help. Undoing the code changes in the Java editor and reparsing in WB does fix it. (This happens with both a normal Composite and a Forms Composite)

Code before the Composite is added:

package test;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.forms.widgets.FormToolkit;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.ui.forms.widgets.Section;

public class TestComposite extends Composite {
	private final FormToolkit formToolkit = new FormToolkit(Display.getDefault());
	private Text txtNewText;

	/**
	 * Create the composite.
	 * @param parent
	 * @param style
	 */
	public TestComposite(Composite parent, int style) {
		super(parent, style);
		setLayout(new FormLayout());
		 
		txtNewText = formToolkit.createText(this, "New Text", SWT.NONE);
		FormData fd_txtNewText = new FormData();
		fd_txtNewText.bottom = new FormAttachment(0, 177);
		fd_txtNewText.right = new FormAttachment(0, 265);
		fd_txtNewText.top = new FormAttachment(0, 49);
		fd_txtNewText.left = new FormAttachment(0, 23);
		txtNewText.setLayoutData(fd_txtNewText);
		
		Button btnNewButton = formToolkit.createButton(this, "New Button", SWT.NONE);
		FormData fd_btnNewButton = new FormData();
		fd_btnNewButton.right = new FormAttachment(0, 348);
		fd_btnNewButton.top = new FormAttachment(0, 220);
		fd_btnNewButton.left = new FormAttachment(0, 153);
		btnNewButton.setLayoutData(fd_btnNewButton);
		
		Section section = formToolkit.createSection(this, Section.TWISTIE | Section.TITLE_BAR);
		FormData fd_section = new FormData();
		fd_section.left = new FormAttachment(0, 26);
		fd_section.bottom = new FormAttachment(txtNewText, 378, SWT.BOTTOM);
		fd_section.right = new FormAttachment(0, 568);
		fd_section.top = new FormAttachment(txtNewText, 99);
		section.setLayoutData(fd_section);
		formToolkit.paintBordersFor(section);
		section.setText("New Section");

	}

	@Override
	protected void checkSubclass() {
		// Disable the check that prevents subclassing of SWT components
	}
}

Adding a Composite to the Section body makes the editor fail.

This error is logged:

Could not retrieve interfaces

org.eclipse.jdt.internal.compiler.problem.AbortCompilation: Pb(347) The type org.eclipse.jface.dialogs.IMessageProvider cannot be resolved. It is indirectly referenced from required type org.eclipse.ui.forms.IMessage
	at org.eclipse.jdt.internal.compiler.problem.ProblemHandler.handle(ProblemHandler.java:159)
	at org.eclipse.jdt.internal.compiler.problem.ProblemHandler.handle(ProblemHandler.java:226)
	at org.eclipse.jdt.internal.compiler.problem.ProblemReporter.handle(ProblemReporter.java:2659)
	at org.eclipse.jdt.internal.compiler.problem.ProblemReporter.isClassPathCorrect(ProblemReporter.java:5012)
	at org.eclipse.jdt.internal.compiler.lookup.UnresolvedReferenceBinding.resolve(UnresolvedReferenceBinding.java:125)
	at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveType(BinaryTypeBinding.java:244)
	at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.superInterfaces(BinaryTypeBinding.java:2476)
	at org.eclipse.jdt.core.dom.TypeBinding.getInterfaces(TypeBinding.java:498)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerTypeBinding.<init>(DesignerTypeBinding.java:155)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:71)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:49)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerTypeBinding.<init>(DesignerTypeBinding.java:146)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:71)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:49)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerMethodBinding.<init>(DesignerMethodBinding.java:70)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:88)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerTypeBinding.<init>(DesignerTypeBinding.java:167)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:71)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:49)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerMethodBinding.<init>(DesignerMethodBinding.java:70)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:88)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerTypeBinding.<init>(DesignerTypeBinding.java:167)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:71)
	at org.eclipse.wb.internal.core.utils.ast.binding.DesignerVariableBinding.<init>(DesignerVariableBinding.java:46)
	at org.eclipse.wb.internal.core.utils.ast.binding.BindingContext.get(BindingContext.java:95)
	at org.eclipse.wb.internal.core.utils.ast.AstParser$3.postVisit(AstParser.java:921)
	at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3315)
	at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:3360)
	at org.eclipse.jdt.core.dom.MethodInvocation.accept0(MethodInvocation.java:223)
	at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3312)
	at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:3360)
	at org.eclipse.jdt.core.dom.ExpressionStatement.accept0(ExpressionStatement.java:136)
	at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:3312)
	at org.eclipse.wb.internal.core.utils.ast.AstParser.copyBindings(AstParser.java:911)
	at org.eclipse.wb.internal.core.utils.ast.AstParser.findNode0(AstParser.java:825)
	at org.eclipse.wb.internal.core.utils.ast.AstParser.findNode(AstParser.java:768)
	at org.eclipse.wb.internal.core.utils.ast.AstParser.parseStatement(AstParser.java:160)
	at org.eclipse.wb.internal.core.utils.ast.AstEditor.addStatement(AstEditor.java:1611)
	at org.eclipse.wb.internal.core.utils.ast.AstEditor.addStatement(AstEditor.java:1565)
	at org.eclipse.wb.core.model.JavaInfo.addExpressionStatement(JavaInfo.java:983)
	at org.eclipse.wb.core.model.JavaInfo.addExpressionStatement(JavaInfo.java:971)
	at org.eclipse.wb.internal.rcp.model.forms.FormToolkitJavaInfoParticipator.addToolkitInvocation(FormToolkitJavaInfoParticipator.java:141)
	at org.eclipse.wb.internal.rcp.model.forms.FormToolkitJavaInfoParticipator.support_paintBordersFor(FormToolkitJavaInfoParticipator.java:103)
	at org.eclipse.wb.internal.rcp.model.forms.FormToolkitJavaInfoParticipator$1.addAfter(FormToolkitJavaInfoParticipator.java:75)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.eclipse.wb.internal.core.utils.reflect.ReflectionUtils.invokeMethod(ReflectionUtils.java:915)
	at org.eclipse.wb.core.model.broadcast.BroadcastSupport.lambda$0(BroadcastSupport.java:213)
	at org.eclipse.wb.core.model.broadcast.JavaEventListener$ByteBuddy$Tr5ZDdud.addAfter(Unknown Source)
	at org.eclipse.wb.internal.core.model.JavaInfoUtils.add(JavaInfoUtils.java:1391)
	at org.eclipse.wb.internal.core.model.JavaInfoUtils.add(JavaInfoUtils.java:1292)
	at org.eclipse.wb.internal.core.model.JavaInfoUtils.add(JavaInfoUtils.java:1222)
	at org.eclipse.wb.internal.rcp.model.widgets.AbstractPositionCompositeInfo.command_CREATE(AbstractPositionCompositeInfo.java:155)
	at org.eclipse.wb.internal.rcp.gef.policy.AbstractPositionCompositeLayoutEditPolicy.command_CREATE(AbstractPositionCompositeLayoutEditPolicy.java:69)
	at org.eclipse.wb.internal.rcp.gef.policy.AbstractPositionCompositeLayoutEditPolicy.command_CREATE(AbstractPositionCompositeLayoutEditPolicy.java:1)
	at org.eclipse.wb.core.gef.policy.layout.position.ObjectPositionLayoutEditPolicy$1.executeEdit(ObjectPositionLayoutEditPolicy.java:53)
	at org.eclipse.wb.core.gef.command.EditCommand.lambda$0(EditCommand.java:52)
	at org.eclipse.wb.internal.core.utils.execution.ExecutionUtils.run(ExecutionUtils.java:306)
	at org.eclipse.wb.core.gef.command.EditCommand.execute(EditCommand.java:52)
	at org.eclipse.gef.commands.CommandStack.execute(CommandStack.java:231)
	at org.eclipse.wb.internal.gef.core.EditDomain$DesignerCommandStack.execute(EditDomain.java:55)
	at org.eclipse.wb.gef.core.tools.Tool.executeCommand(Tool.java:172)
	at org.eclipse.wb.gef.core.tools.AbstractCreationTool.handleButtonUp(AbstractCreationTool.java:65)
	at org.eclipse.wb.gef.core.tools.Tool.mouseUp(Tool.java:270)
	at org.eclipse.gef.EditDomain.mouseUp(EditDomain.java:288)
	at org.eclipse.wb.internal.gef.core.EditDomain.mouseUp(EditDomain.java:233)
	at org.eclipse.wb.internal.gef.graphical.EditEventManager.lambda$2(EditEventManager.java:155)
	at org.eclipse.wb.internal.draw2d.EventManager.delayEvent(EventManager.java:338)
	at org.eclipse.wb.internal.gef.graphical.EditEventManager.dispatchMouseReleased(EditEventManager.java:143)
	at org.eclipse.draw2d.LightweightSystem$EventHandler.mouseUp(LightweightSystem.java:598)
	at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:262)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4364)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1217)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4162)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3750)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1147)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1038)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:677)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:583)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:185)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:219)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:149)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:115)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:467)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:298)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:615)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:563)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1415)

Code after the Composite is added to the Section body:

package test;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.forms.widgets.FormToolkit;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.ui.forms.widgets.Section;

public class TestComposite extends Composite {
	private final FormToolkit formToolkit = new FormToolkit(Display.getDefault());
	private Text txtNewText;

	/**
	 * Create the composite.
	 * @param parent
	 * @param style
	 */
	public TestComposite(Composite parent, int style) {
		super(parent, style);
		setLayout(new FormLayout());
		 
		txtNewText = formToolkit.createText(this, "New Text", SWT.NONE);
		FormData fd_txtNewText = new FormData();
		fd_txtNewText.bottom = new FormAttachment(0, 177);
		fd_txtNewText.right = new FormAttachment(0, 265);
		fd_txtNewText.top = new FormAttachment(0, 49);
		fd_txtNewText.left = new FormAttachment(0, 23);
		txtNewText.setLayoutData(fd_txtNewText);
		
		Button btnNewButton = formToolkit.createButton(this, "New Button", SWT.NONE);
		FormData fd_btnNewButton = new FormData();
		fd_btnNewButton.right = new FormAttachment(0, 348);
		fd_btnNewButton.top = new FormAttachment(0, 220);
		fd_btnNewButton.left = new FormAttachment(0, 153);
		btnNewButton.setLayoutData(fd_btnNewButton);
		
		Section section = formToolkit.createSection(this, Section.TWISTIE | Section.TITLE_BAR);
		FormData fd_section = new FormData();
		fd_section.left = new FormAttachment(0, 26);
		fd_section.bottom = new FormAttachment(txtNewText, 378, SWT.BOTTOM);
		fd_section.right = new FormAttachment(0, 568);
		fd_section.top = new FormAttachment(txtNewText, 99);
		section.setLayoutData(fd_section);
		formToolkit.paintBordersFor(section);
		section.setText("New Section");
		section.setExpanded(true);
		
		Composite composite = new Composite(section, SWT.NONE);
		formToolkit.adapt(composite);
		formToolkit.paintBordersFor(composite);
		section.setClient(composite);

	}

	@Override
	protected void checkSubclass() {
		// Disable the check that prevents subclassing of SWT components
	}
}

Adding a Forms Composite has slightly different code but the same outcome.

package test;

import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.forms.widgets.FormToolkit;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.ui.forms.widgets.Section;

public class TestComposite extends Composite {
	private final FormToolkit formToolkit = new FormToolkit(Display.getDefault());
	private Text txtNewText;

	/**
	 * Create the composite.
	 * @param parent
	 * @param style
	 */
	public TestComposite(Composite parent, int style) {
		super(parent, style);
		setLayout(new FormLayout());
		 
		txtNewText = formToolkit.createText(this, "New Text", SWT.NONE);
		FormData fd_txtNewText = new FormData();
		fd_txtNewText.bottom = new FormAttachment(0, 177);
		fd_txtNewText.right = new FormAttachment(0, 265);
		fd_txtNewText.top = new FormAttachment(0, 49);
		fd_txtNewText.left = new FormAttachment(0, 23);
		txtNewText.setLayoutData(fd_txtNewText);
		
		Button btnNewButton = formToolkit.createButton(this, "New Button", SWT.NONE);
		FormData fd_btnNewButton = new FormData();
		fd_btnNewButton.right = new FormAttachment(0, 348);
		fd_btnNewButton.top = new FormAttachment(0, 220);
		fd_btnNewButton.left = new FormAttachment(0, 153);
		btnNewButton.setLayoutData(fd_btnNewButton);
		
		Section section = formToolkit.createSection(this, Section.TWISTIE | Section.TITLE_BAR);
		FormData fd_section = new FormData();
		fd_section.left = new FormAttachment(0, 26);
		fd_section.bottom = new FormAttachment(txtNewText, 378, SWT.BOTTOM);
		fd_section.right = new FormAttachment(0, 568);
		fd_section.top = new FormAttachment(txtNewText, 99);
		section.setLayoutData(fd_section);
		formToolkit.paintBordersFor(section);
		section.setText("New Section");
		section.setExpanded(true);
		
		Composite composite = formToolkit.createComposite(section, SWT.NONE);
		formToolkit.paintBordersFor(composite);
		section.setClient(composite);

	}

	@Override
	protected void checkSubclass() {
		// Disable the check that prevents subclassing of SWT components
	}
}

Closing Eclipse and reopening the designer have no effect.

Since the error mentioned jface, I tried adding more jars to the project but that didn't help.

[jeffecom]

If I comment out the line section.setExpanded(true); then the editor works again.

Deleting the Composite in code doesn't help. The section.setExpanded(true); seems to be the problem.

Changing the line to section.setExpanded(false); also reproduces the error. Only removing that line fixes it.

If you set the section style to Expanded, then the designer works. In that case it doesn't add section.setExpanded() to the code.

If section.setExpanded() is added manually, the designer fails.

[ptziegler]

I think you're describing several problems at once here, so let's split this up a bit:

Only the simplest of controls I created in previous version seem to display properly in the WB editor.

Since when do those issues show up and what type of controls do you try to create? Are there any additional errors being logged?

This error is logged:

org.eclipse.jdt.internal.compiler.problem.AbortCompilation: Pb(347) The type org.eclipse.jface.dialogs.IMessageProvider cannot be resolved. It is indirectly referenced from required type org.eclipse.ui.forms.IMessage
...

I don't think there is much WindowBuilder can do on this side. This is an error directly thrown by JDT, caused by an incomplete classpath. The solution is effectively what you already did: To add the missing dependencies to the classpath.

If I comment out the line section.setExpanded(true); then the editor works again.

That's indeed interesting, but I get the impression that this is only the symptom, rather than the cause.

The cause of the "blank" editor is due to Composite.isLayoutDeferred being set together with the expanded property . This causes the screenshot to be taken before the layout has been calculated, which means all widgets still have zero size.

Forcing the deferred layouts to be executed before taking the screenshot seems to do the trick, but that might just be delaying the problem. I can have a look over the next few days to get a better overview.

[jeffecom]

Thank you for looking at this.

I'm not even sure what jars I should have in the app. It's using SWT, Forms, and Draw2D so I added these jars:

Some of these were added in desperation based on AI questions, to see if they make a difference. Is there an official guide for standalone SWT apps? I've looked but there doesn't seem to be anything official and/or recent.

Since when do those issues show up and what type of controls do you try to create? Are there any additional errors being logged?

I have had problems with WB for years, but I think it got really bad after 2023 or 2024. I kind of gave up on it at that point and did other things. I'd have to check the code and make a test case for the other errors, but it's possible this error we are looking at now is the most common. The fact it was reproducible with such a simple case is encouraging. Some of the other controls that fail to render are subclasses of Control 5 levels deep, etc so much less clear what's happening.

I'm happy to wait for a fix for this issue and then do more testing to identify any other problems. I suspect that most of my failing controls have Forms Sections in them so this would be a good fix.

[ptziegler]

Is there an official guide for standalone SWT apps? I've looked but there doesn't seem to be anything official and/or recent.

WindowBuilder doesn't really distinguish between RCP and pure SWT applications. It only cares about all dependencies being in the classpath. The "normal" workflow when working with SWT is to create an "SWT/JFace" project. WindowBuilder will then automatically add all required libraries to the classpath.

Given that you already have a project, I would simply create a "dummy" project and then update the .classpath file of your "real" project. I've also just migrated the documentation to AsciiDoc, so you can read up more here.

I'm happy to wait for a fix for this issue and then do more testing to identify any other problems. I suspect that most of my failing controls have Forms Sections in them so this would be a good fix.

That would be great! This is obviously also frustrating from my side to hear about issues with the SWT integration existing for two years without anyone ever bringing them up... :/

[ptziegler]

@jeffecom Can you try out tomorrows nightly build to check if this issue is fixed on your side as well? At least locally, the layout is correctly calculated, even if the "expanded" property is set.

[jeffecom]

I installed the nightly update using MarketPlace and it worked! I tried a few of my more complex Forms controls and they work again now too. These controls have deep inheritance levels and multiple custom controls, all using Forms and Sections - so if they work I think most/all of them will.

Some errors might be due to my code, as I started this project a long time ago and WB changed its requirements a few times. e.g. very old versions could handle any type of constructor but later changed to require simple (parent, style) constructor - I think that was about when Google took over the development. I still have some with different constructors, mainly using enums for styling and config. My question: are such non-standard constructors definitely forbidden now? Should I report them if they fail or should I refactor my code to always use (parent, style) constructors everywhere? Just asking so I don't waste your time reporting spurious bugs.

There are some cases where the control being edited has a (parent, style) constructor, but it's parents use constructors with a list of hard-coded enum values (depending on subclass). These would edit ok in WB, but sometimes the parents wouldn't (which was alright as they are sometimes simple). Is that a forbidden practice now?

Thank you for the fix. It is very much appreciated! WB is totally awesome (when it's working). I want to help keep it working, so I'll check out my other controls and look for more bugs to report.

[jeffecom]

Further to the constructor thing, I notice it asks for you to select a constructor as an entry point if it can't find the default (parent, style) one.
I will check all my controls and see if there is anything else worth reporting, but all the ones I've checked so far look good.

[ptziegler]

Non-standard constructors aren't forbidden per-se, but WindowBuilder might have difficulty finding an entry point, just as you mentioned. Depending on the complexity of the widget, it might be necessary to add them as distinct components.

I'd probably have to make a small example to see how exactly the editor responds to such widgets. But the most reliable solution is definitely to always at least have a (parent, style) constructor.