Is it possible to open a Dialog while closing another Dialog?

[basilevs]

My Eclipse-based application has hanged indefintely in an method close() of a Dialog. I suspect this is caused by the fact, that the method attempts (indirectly) to open another Dialog. I was going to file a bug, but I don't understand what is the expected behavior in this case. Can a Dialog show another Dialog? If yes, then why not from some focus listener that fires when dialog is closed?

"main" #1 prio=6 os_prio=31 cpu=5324.41ms elapsed=80.28s tid=0x0000000158011e00 nid=0x103 runnable  [0x000000016b76b000]
   java.lang.Thread.State: RUNNABLE
	at org.eclipse.swt.internal.cocoa.OS.objc_msgSend_bool(Native Method)
	at org.eclipse.swt.internal.cocoa.NSRunLoop.runMode(NSRunLoop.java:40)
	at org.eclipse.swt.widgets.Display.sleep(Display.java:5206)
	at org.eclipse.jface.window.Window.runEventLoop(Window.java:824)
	at org.eclipse.jface.window.Window.open(Window.java:799)
	at org.eclipse.jface.dialogs.MessageDialog.open(MessageDialog.java:608)
	at org.eclipse.ui.texteditor.AbstractTextEditor.handleEditorInputChanged(AbstractTextEditor.java:4689)
	at org.eclipse.ui.texteditor.StatusTextEditor.handleEditorInputChanged(StatusTextEditor.java:290)
	at org.eclipse.ui.texteditor.AbstractDecoratedTextEditor.handleEditorInputChanged(AbstractDecoratedTextEditor.java:1502)
	at org.eclipse.ui.texteditor.AbstractTextEditor.sanityCheckState(AbstractTextEditor.java:4865)
	at org.eclipse.ui.texteditor.StatusTextEditor.sanityCheckState(StatusTextEditor.java:276)
	at org.eclipse.ui.texteditor.AbstractTextEditor.safelySanityCheckState(AbstractTextEditor.java:4843)
	at org.eclipse.ui.texteditor.AbstractTextEditor$ActivationListener.handleActivation(AbstractTextEditor.java:983)
	at org.eclipse.ui.texteditor.AbstractTextEditor$ActivationListener.partActivated(AbstractTextEditor.java:948)
	at org.eclipse.ui.internal.PartService$1.run(PartService.java:85)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.ui.internal.PartService.partActivated(PartService.java:82)
	at org.eclipse.ui.internal.WorkbenchWindow$WWinPartService.partActivated(WorkbenchWindow.java:3151)
	at org.eclipse.ui.internal.WorkbenchPage$2.run(WorkbenchPage.java:4887)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.ui.internal.WorkbenchPage.firePartActivated(WorkbenchPage.java:4884)
	at org.eclipse.ui.internal.WorkbenchPage$E4PartListener.partActivated(WorkbenchPage.java:215)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl$2.run(PartServiceImpl.java:250)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartActivated(PartServiceImpl.java:247)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:780)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:686)
	at org.eclipse.e4.ui.internal.workbench.swt.AbstractPartRenderer.activate(AbstractPartRenderer.java:95)
	at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.lambda$0(ContributedPartRenderer.java:63)
	at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer$$Lambda$564/0x000000080114ee90.handleEvent(Unknown Source)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4643)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1524)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1547)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1532)
	at org.eclipse.swt.widgets.Shell.setActiveControl(Shell.java:1633)
	at org.eclipse.swt.widgets.Shell.setActiveControl(Shell.java:1596)
	at org.eclipse.swt.widgets.Control.sendFocusEvent(Control.java:3463)
	at org.eclipse.swt.widgets.Canvas.sendFocusEvent(Canvas.java:80)
	at org.eclipse.swt.widgets.Display.checkFocus(Display.java:748)
	at org.eclipse.swt.widgets.Shell.becomeKeyWindow(Shell.java:533)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:6114)
	at org.eclipse.swt.internal.cocoa.OS.objc_msgSend(Native Method)
	at org.eclipse.swt.internal.cocoa.NSWindow.close(NSWindow.java:57)
	at org.eclipse.swt.widgets.Shell.destroyWidget(Shell.java:818)
	at org.eclipse.swt.widgets.Widget.release(Widget.java:1373)
	at org.eclipse.swt.widgets.Control.release(Control.java:2987)
	at org.eclipse.swt.widgets.Widget.dispose(Widget.java:695)
	at org.eclipse.jface.window.Window.close(Window.java:335)
	at org.eclipse.jface.dialogs.Dialog.close(Dialog.java:987)
	at org.eclipse.jface.dialogs.ProgressMonitorDialog.close(ProgressMonitorDialog.java:347)
	at org.eclipse.jface.dialogs.ProgressMonitorDialog.finishedRun(ProgressMonitorDialog.java:556)
	at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:473)
	at org.eclipse.rcptt.ui.launching.LaunchUtils.doLaunch(LaunchUtils.java:379)
	at org.eclipse.rcptt.ui.launching.LaunchUtils$3.run(LaunchUtils.java:368)
	at org.eclipse.rcptt.ui.launching.LaunchUtils.runInUI(LaunchUtils.java:419)
	at org.eclipse.rcptt.ui.launching.LaunchUtils.launch(LaunchUtils.java:366)
	at org.eclipse.rcptt.ui.launching.aut.BasicAUTComposite.launch(BasicAUTComposite.java:174)
	at org.eclipse.rcptt.ui.launching.aut.AUTViewComposite$1.run(AUTViewComposite.java:48)
	at org.eclipse.jface.action.Action.runWithEvent(Action.java:474)
	at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:581)
	at org.eclipse.jface.action.ActionContributionItem.lambda$5(ActionContributionItem.java:454)
	at org.eclipse.jface.action.ActionContributionItem$$Lambda$507/0x000000080112ba80.handleEvent(Unknown Source)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4643)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1524)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1547)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1532)
	at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1325)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4410)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3986)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1151)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1042)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:152)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:639)
	at org.eclipse.ui.internal.Workbench$$Lambda$230/0x0000000800e259d0.run(Unknown Source)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:546)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:143)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:109)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:439)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:271)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0([email protected]/Native Method)
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke([email protected]/NativeMethodAccessorImpl.java:77)
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke([email protected]/DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke([email protected]/Method.java:568)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:651)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:588)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1459)

UPDATE:
I've failed to reproduce the problem with a pure SWT test:

	boolean[] test = {false};
	shell.open();
	messageBox.setMessage("Second dialog");
	shell.addFocusListener(new FocusAdapter() {
		@Override
		public void focusGained(FocusEvent e) {
			shell.setText("Focus gained");
			messageBox.open(); // Properly terminates
			shell.setText("Success");
			test[0]=true;
			shell.close();
		}
	});
	MessageBox anotherMessageBox = new MessageBox(shell, SWT.NULL);
	anotherMessageBox.setMessage("First dialog");
	anotherMessageBox.open();  // Shell focus is lost, then regained once user closes the box
	Assert.assertTrue(test[0]);

	while (!shell.isDisposed()) {
		shell.getDisplay().readAndDispatch();
	}

It seems like use of JFace Dialog is essential to reproduce

[iloveeclipse]

There are always corner cases where native and SWT code can't do things one would like to do.
I remember on GTK there is a problem to do some widget operations during "onpaint" callback, so I assume on Mac this can be similar with "close". But could be also a bug in SWT and/or Mac or both.

[laeubi]

@basilevs in general for such actions it is good to simply use Display.asyncExec and perform the new operation there. This allows the current pending events to finish before the next action (showing another dialog) is performed.