How to handle browser event in gwt?

I am using GWT 2.3 with GWTP plugin in my application.In this
application I want to block browser back and forth event.For this I
got some java script code.But this code is onLoad() and onUnLoad() of
the html page.As application is a GWT application there is only one
html which myapplication.html.So it is loaded only one time rest
history token fire depends upon code. I want to block browser event
for each and every history token in the system.

Scenario is like below:

My first history token is index.So first my index page is loaded.Now
there is login panel on index page.After success full login I fire
another history token named userpage.So my user page is loaded.On back
click a history token index is fired again my index page loaded
again.And now If I click on forth of browser then again my user page
is loaded.

So for back I don't want to fire last history token again and same for
the forth not next history token. If history token would fired from
code instead of browser event (back and forth) then it should work in
proper manner.So just want to handle browser event.

For handling history I also overridden method on value change.So my
every history token is went to on Value change but I am not able to
identify, that the history token is fired is from browser event or
from code.

Please help me out. Thanks in advance.

--
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.