Resize handling. Getting info on when resize is finished vs started?

[kram]

I cant seem to find the documentation on how to detect ( if possible ) resize handling of a browser window, to differentiate the start of the resize versus the end of the resize.

Can someone toss me the URL which explains this?

BTW I currently use listeners on my viewport such as
listeners: {
'resize': function () {
.....

but Im trying to determine if I can get more info.

[Animal]

Usually you don't need this info.

Components will relay themselves upon resize (as long as they are within a Container configured to perform sizing on its child Components).

What do you need this information for?

http://docs.sencha.com/ext-js/4-0/#!/api/Ext.EventManager-method-onWindowResize