Vista - Refresh ui as DoEvents

I'm searching a way to force screen to refresh in the same way as doevents().

In fact when navigating in our application, whe have a lot a refresh problem.

For example a click on a menu item, instanciate a new usercontrol and insert
it in the current window . while the usecontrol is instanciating, it does
some jobs ( ie :load data from a far database ) which can take seconds.
During this time the menu item stay open ( not refreshed) and some blocks on
the screen are not painted.

Note that we host some winform elements in our UI.

I tried to use DoEvents(), now the winform elements are refreshed quickly
but not the avalon ui elements.

I know that a good solution should be to do the loading tasks using
background worker, but shortly we need a simpliest solution.