SmartGWT tab losing GWT based contents - gwt

Question

I have written very basic GWT application where SmartGWt tabs render with label on both tabs.
Problem I am facing here is, when I put GWT based label in second tab and reload application, first tab renders SmartGWT based label but when i click on second tab to look GWT label, it doesn't appear and also I am surprised why first tab content is removed as It was appearing earlier before clicking on second tab.
Please have a look into below code.
package com.test.client;
import com.smartgwt.client.widgets.Canvas;
import com.smartgwt.client.widgets.tab.Tab;
import com.smartgwt.client.widgets.tab.TabSet;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
public class TestGWT implements EntryPoint
{
public void onModuleLoad()
{
TabSet tabSet = new TabSet();
tabSet.setWidth("400px");
Tab tab1 = new Tab("Tab1");
Canvas pane = new Canvas();
pane.addChild(new com.smartgwt.client.widgets.Label("test label"));
tab1.setPane(pane);
Tab tab2 = new Tab("Tab2");
Canvas pane2 = new Canvas();
pane2.addChild(new Label("test label2")); // I need to put GWT widget in SmartGWT tab but it does not render in this tab. Also, it removes contents from first tab
tab2.setPane(pane2);
tabSet.addTab(tab1);
tabSet.addTab(tab2);
RootPanel.get("testid").add(tabSet);
}
}
When I set second SmartGWT tab to appear first which has GWT widget then things are working fine.
I am using GWT-2.6.1
Please share your thoughts here!
Regards,
Shobhit

Answer 1

Although I agree on the cause of the problem being RootPanel.get("testid").add(tabSet), the solution is replacing that line with:
tabSet.show();
Keep in mind that in SmartGWT, you should add components to other components using add(). Trying to add components using their IDs is prone to errors.
Finally, keep in mind that Isomorphic discourages mixing SmartGWT's components with components from other libraries. While this is unavoidable sometimes, if you can avoid it in your application, you should, because this is a very common source for bugs. See my comments below for additional sources for these claims.

Answer 2

The problem is adding the TabSet to the RootPanel. So you receive an
A widget that has an existing parent widget may not be added to the detach list.
error.
Change RootPanel.get("testid").add(tabSet); to
tabSet.setHtmlElement((Element) Document.get().getElementById("testid"));
tabSet.draw();
and it will work fine.