Re: 'null' is null or not an object error

why don't you use a CardLayout for your center panel, and instead of
removing and adding your widget to the "ceter part" .. you just
activate the ones corresponding to the menu option.

Menu :
[menu 1]
[menu 2]

Center Panel:
[menu 1 panel]
[menu 2 panel]

Select [menu 1] --> Center Panel. setActiveItem (menu 1 panel);
Select [menu 2] --> Center Panel. setActiveItem (menu 12panel);

no need for remove/add/layout calls.

More GWT hits you can find here:
http://ui-programming.blogspot.com/2009/12/update-your-application-to-gwt-20.html

Cheers!

PS: if you like the solution, don't be shy to click on few ads, you
know, for fun - thx!

--
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To post to this group, send email to google-web-toolkit@googlegroups.com.
To unsubscribe from this group, send email to google-web-toolkit+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.