I had this problem when I created a Window (Smartgwt) and put a DynamicForm (Smartgwt) in this Window, In this DynamicForm, I have a CanvasItem (Smartgwt) in which I put a RichTextArea (GWT). And when I press "ESC", I can quit the Window (Smartgwt) without probleme. But when I press "F5" to refresh my application, the browser pops up a exception saying "com.google.gwt.user.client.ui.AttachDetachException". To solve this problem, I do the following: public class MailWindow extends Window { public MailWindow(){ this.addCloseClickHandler(new CloseClickHandler() { public void onCloseClick(CloseClientEvent event) { form.getRichTextArea().removeFromParent(); MailWindow.this.destroy(); } }); } } Which solved my problem! :) Kewei