Hi,
It seems like the only way to set the size of the OverviewMap dijit is during its construction. When the map is resized, the proportion of the overviewMap against the main map won't stay. The OverviewMap will stay the same size no matter what. The only way I can think of is to destroy the existing OverviewMap dijit instance, and create another one with the new size, which is awkward. I think the API should provide a resize method. In addition, it will be nice if the API can provide some events if the user likes to catch the events and do something with it.
Thanks,
Jason Zou