Changed declaration of nsIPrivateDOMEvent without changing IID

Hi,

I do an extension in c++. My extension is for Thunderbird (TB) and it 
will works with TB2 (Gecko 1.8) and TB3 (Gecko 1.9).

I’m using interface nsIPrivateDOMEvent.

I noticed that this interface was changed, but IID wasn’t changed. Is it 
reason or is it a mistake?

Because I do extension in c++ I need to distinguish which interface I 
can use. I can’t do this when both have the same iid.

Following methods declarations are changed:
   - IsDispatchStopped
   - GetInternalNSEvent
   - HasOriginalTarget


***************************************************
Gecko 1.8:
#define NS_IPRIVATEDOMEVENT_IID \
{ /* 25e6626c-8e54-409b-87b5-2beceaac399e */ \
0x25e6626c, 0x8e54, 0x409b, \
{0x87, 0xb5, 0x2b, 0xec, 0xea, 0xac, 0x39, 0x9e} }

class nsIPrivateDOMEvent : public nsISupports
{
public:
   NS_DEFINE_STATIC_IID_ACCESSOR(NS_IPRIVATEDOMEVENT_IID)

   NS_IMETHOD DuplicatePrivateData() = 0;
   NS_IMETHOD SetTarget(nsIDOMEventTarget* aTarget) = 0;
   NS_IMETHOD SetCurrentTarget(nsIDOMEventTarget* aTarget) = 0;
   NS_IMETHOD SetOriginalTarget(nsIDOMEventTarget* aTarget) = 0;
   NS_IMETHOD IsDispatchStopped(PRBool* aIsDispatchPrevented) = 0;
   NS_IMETHOD GetInternalNSEvent(nsEvent** aNSEvent) = 0;
   NS_IMETHOD HasOriginalTarget(PRBool* aResult)=0;
   NS_IMETHOD SetTrusted(PRBool aTrusted)=0;
};

Gecko:1.9
#define NS_IPRIVATEDOMEVENT_IID \
{ /* 25e6626c-8e54-409b-87b5-2beceaac399e */ \
0x25e6626c, 0x8e54, 0x409b, \
{0x87, 0xb5, 0x2b, 0xec, 0xea, 0xac, 0x39, 0x9e} }

class nsIPrivateDOMEvent : public nsISupports
{
public:
    NS_DECLARE_STATIC_IID_ACCESSOR(NS_IPRIVATEDOMEVENT_IID)

    NS_IMETHOD DuplicatePrivateData() = 0;
    NS_IMETHOD SetTarget(nsIDOMEventTarget* aTarget) = 0;
    NS_IMETHOD SetCurrentTarget(nsIDOMEventTarget* aTarget) = 0;
    NS_IMETHOD SetOriginalTarget(nsIDOMEventTarget* aTarget) = 0;
    NS_IMETHOD_(PRBool) IsDispatchStopped() = 0;
    NS_IMETHOD_(nsEvent*) GetInternalNSEvent() = 0;
    NS_IMETHOD_(PRBool) HasOriginalTarget() = 0;
    NS_IMETHOD SetTrusted(PRBool aTrusted) = 0;
};