Tabbed Document Interface (TDI)
The current way of managing multiple documents is via tabs (like web browsers do), however I think it should be done better than a hack on MDI to change the cosmetics. It should go beyond the current MDI limitations by:
1. managing child TDI forms locally to the component / parent TDI form
2. allow multiple TDI parent forms in an application
3. the TDI parent need not be the main form
4. ribbon controls (both the native and 3rd party e.g. DevExpress) placed on the child TDI can merge onto the TDI parent form's ribbon
5. the tabs can be placed into container controls, not just onto the empty area of the form to allow for more custom alignment scenarios for surrounding controls
6. The technology should be available in FireMonkey, not just VCL.