Hi H, I just built an application using the approach you mention (tabbed with an MDI on the outside). I find that this interface works extremely well for a large number of applications. In particular, the ability to constantly show navigation / menu bar / etc on the MDI parent. I used Infragistics tool suite to build out the interface - they have a component that actually makes MDI children tabbed - and abstracts most of the work for you. I highly recommend checking it out! The component is called UltraTabbedMDIManager ...

One thing you could do is to modify the SQL query so that 'ALL' is in the datatable. I.e. " SELECT Value1 FROM Table1 UNION ALL SELECT 'ALL' " Then the option value will be in the datatable and you can select it.