private void openInMemoryHtmlEditor(String content, String name, String toolTip) {
	IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
	IWorkbenchPage page = window != null ? window.getActivePage() : null;
	if (page != null) {
		try {
			IEditorDescriptor editorDescriptor = PlatformUI.getWorkbench()
					.getEditorRegistry().getDefaultEditor("view-source.html"); // get default editor for .html //$NON-NLS-1$
			String editorId;
			if (editorDescriptor != null && editorDescriptor.isInternal()) {
				editorId = editorDescriptor.getId();
			} else {
				editorId = "org.eclipse.ui.DefaultTextEditor"; //$NON-NLS-1$
			}

			IStorage storage = new StringStorage("", // see the long comment below to know why an empty storage is created //$NON-NLS-1$
					"view-source.html"); // .html extension is needed to enable code highlighting in the WTP HTML editor //$NON-NLS-1$
			IStorageEditorInput input = new StringInput(storage, name, toolTip);
			IEditorPart editor = page.openEditor(input, editorId);
			
			/* We change content of the editor AFTER the editor is created
			 * as a workaround for the following WTP bug.
			 * The essence of the bug is that if given HTML page contains a link
			 * to an external DTD, then WTP HTML editor tries to access this DTD before the editor
			 * is created and freezes UI.
			 * See http://www.eclipse.org/forums/index.php/m/639937/
			 */
			IDocument doc = null;
			ITextEditor textEditor = null;
			if (editor instanceof ITextEditor) {
				textEditor = (ITextEditor) editor;
			} else {
				textEditor = (ITextEditor) editor.getAdapter(ITextEditor.class);
			}
			
			if (textEditor != null) {
				doc = textEditor.getDocumentProvider().getDocument(input);// <<<<----- THE PROBLEM APPEARS HERE
			}

			if (doc != null) {
				doc.set(content);
				editor.doSave(null); // reset resource-changed marker
			}
		} catch (PartInitException e) {
			Activator.logError(e.getMessage(), e);
		}
	} else {
		Activator.logError("Cannot obtain workbench page", null);
	}
}