How support register display in a custom debug engine

Several days ago, I asked the questions in the new group, yesterday a MS guy answered.

Jim Glass [MSFT] wrote:

> Michael,
>
> Question: "I read through the documents and can not find a way to show the
> registers in the Register Window. We want to provide information from the
> DE for the registers. Is it possible? Which interface should I start with?"
>
> Answer: Registers are obtained by calling IDebugStackFrame2::EnumProperties
> with a refiid of guidFilterRegisters (defined in msdbg.h as an external
> value).  EnumProperties is called whenever the Registers Window needs to be
> updated.  This update will occur only when the program being debug is
> stopped, either because the user paused execution or a breakpoint was hit.

Seems to be 'undocumented' again...
Calling IDebugStackFrame2::EnumProperties with a refiid of guidFilterRegisters returns an IEnumDebugPropertyInfo2 object which contains the enum of properties (IDebugProperty2) for different register types. Each one of them represents a register type (like CPU, CPU segment, mmx) and has children represent the registers. Calling IDebugProperty2::EnumChildren to get another enum for the registers.