1. Top features for multi-context debugging
Duplicating and pinning (locking) debugger views to a context
Multiple context providers associated with Debug view, and presented using colors, icon overlays or other visual indicators
Changing the context provider for debugger views and having a visual indicator of active provider (color, etc.)
Ability to change the active context when focus is given to a pinned view.

2. Features needed for an external multi-context debugging implementation.
Arbitrary context providers (not associated with a specific view)
Extending debugger views to change the debug context provider
Extending debugger views to change decoration (title, background or frame color, etc.)

3. What lives where? What goes in the platform? What goes in a plug-in?
Can our changes be used by other debugger implementations (JDT, CDT, PTP, etc)