The project filter should be able to be different for each tab open in RV&S. Example - you have a query open for all sub level documents. You set the project filter to the projects you are working on. Then in tab 2 you have a query open for all Layer 2 documents. You are working on the layer 2 documents in a different set of projects. You should be able to configure the project filter so it doesn't change the project filter on the first tab.