How to add a "Please Wait..." message when populating a TreeView

[jeeji]

Hi

I have a web application which has a TreeView control from the ASP
WebControls namespace. The creation of the TreeView is coded in C#.
For some of the nodes, I have set the property PopulateOnDemand, since
this is a time consuming operation, and not all nodes should be
populated.

But whenever I click in a node that is to be populated on demand, it
takes so long time because it is performed on the server side. And
because it takes a long time, nothing happens on the client side,
after clicking on the node to be popluated.
I would like to give the user a "Please Wait..." message as the child
of the node that was clicked. And when the operation is finished, it
replaces the "Please Wait..." message with the resulting child node.

Is that not possible with those controls I am using?

Thanks a lot

Jeeji