nsIWindowProvider

The nsIWindowProvider interface exists so that the window watcher’s default
behavior of opening a new window can be easly modified. When the window
watcher needs to open a new window, it will first check with the
nsIWindowProvider it gets from the parent window. If there is no provider
or the provider does not provide a window, the window watcher will proceed
to actually open a new window.

Methods

provideWindow(aParent, aChromeFlags, aCalledFromJS, aPositionSpecified, aSizeSpecified, aURI, aName, aFeatures, aWindowIsNew)

A method to request that this provider provide a window. The window
returned need not to have the right name or parent set on it; setting
those is the caller’s responsibility. The provider can always return null
to have the caller create a brand-new window.

   When making decisions based on aURI, note that even when it's not  
   null, aURI may not represent all relevant information about the  
   load.  For example, the load may have extra load flags, POST data,  
   etc.

@throw NS_ERROR_ABORT if the caller should cease its attempt to open a new
window.

@see nsIWindowWatcher for more information on aFeatures.
@see nsIWebBrowserChrome for more information on aChromeFlags.

Parameters

aParent	Must not be null. This is the window that the caller wants to use as the parent for the new window. Generally, nsIWindowProvider implementors can expect to be somehow related to aParent; the relationship may depend on the nsIWindowProvider implementation.
aChromeFlags	The chrome flags the caller will use to create a new window if this provider returns null. See nsIWebBrowserChrome for the possible values of this field.
aPositionSpecified	Whether the attempt to create a window is trying to specify a position for the new window.
aSizeSpecified	Whether the attempt to create a window is trying to specify a size for the new window.
aURI	The URI to be loaded in the new window (may be NULL). The nsIWindowProvider implementation must not load this URI into the window it returns. This URI is provided solely to help the nsIWindowProvider implementation make decisions; the caller will handle loading the URI in the window returned if provideWindow returns a window.
aName	The name of the window being opened. Setting the name on the return value of provideWindow will be handled by the caller; aName is provided solely to help the nsIWindowProvider implementation make decisions.
aFeatures	The feature string for the window being opened. This may be empty. The nsIWindowProvider implementation is allowed to apply the feature string to the window it returns in any way it sees fit. See the nsIWindowWatcher interface for details on feature strings.
aWindowIsNew	[out] Whether the window being returned was just created by the window provider implementation. This can be used by callers to keep track of which windows were opened by the user as opposed to being opened programmatically. This should be set to false if the window being returned existed before the provideWindow() call. The value of this out parameter is meaningless if provideWindow() returns null.

Returns

A window the caller should use or null if the caller should just create a new window. The returned window may be newly opened by the nsIWindowProvider implementation or may be a window that already existed.