When you run JBoss Tools visual page editor on Mac OS 10.4 folllowing error possible.
Solution is update java on your env atleast to java 1.5.07(OSX Java Update 5) or never
Here Link to Java Updates
org.eclipse.swt.SWTError: No more handles at org.eclipse.swt.SWT.error(SWT.java:3910) at org.eclipse.swt.SWT.error(SWT.java:3799) at org.eclipse.swt.SWT.error(SWT.java:3770) at org.eclipse.swt.browser.MozillaDelegate.getHandle(MozillaDelegate.java:147) at org.eclipse.swt.browser.Mozilla.create(Mozilla.java:1310) at org.eclipse.swt.browser.Browser.<init>(Browser.java:119) at org.jboss.tools.vpe.xulrunner.browser.XulRunnerBrowser.<init>(XulRunnerBrowser.java:88) at org.jboss.tools.vpe.xulrunner.editor.XulRunnerEditor.<init>(XulRunnerEditor.java:135) at org.jboss.tools.vpe.editor.mozilla.MozillaEditor$6.<init>(MozillaEditor.java:419) at org.jboss.tools.vpe.editor.mozilla.MozillaEditor.createPartControl(MozillaEditor.java:419) at org.jboss.tools.vpe.editor.VpeEditorPart.createVisualEditor(VpeEditorPart.java:931) at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditor.pageChange(JSPMultiPageEditor.java:240) at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditor.createPages(JSPMultiPageEditor.java:431) at org.jboss.tools.jst.jsp.jspeditor.JSPMultiPageEditorPart.createPartControl(JSPMultiPageEditorPart.java:125) at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:662) at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:462) at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595) at org.eclipse.ui.internal.EditorAreaHelper.setVisibleEditor(EditorAreaHelper.java:271) at org.eclipse.ui.internal.EditorManager.setVisibleEditor(EditorManager.java:1417) at org.eclipse.ui.internal.EditorManager$5.runWithException(EditorManager.java:942) at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3342) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3071) at org.eclipse.ui.application.WorkbenchAdvisor.openWindows(WorkbenchAdvisor.java:803) at org.eclipse.ui.internal.Workbench$28.runWithException(Workbench.java:1384) at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3342) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3071) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2316) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194) 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:368) 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:585) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311) at org.eclipse.equinox.launcher.Main.main(Main.java:1287)