Indicates whether the native implementation should proceed with a
pending, native focus request. Before changing the focus at the native
level, the AWT implementation should always call this function for
permission. This function will reject the request if a duplicate request
preceded it, or if the specified heavyweight Component already owns the
focus and no native focus changes are pending. Otherwise, the request
will be approved and the focus request list will be updated so that,
if necessary, the proper descendant will be focused when the
corresponding FOCUS_GAINED event on the heavyweight is received.
An implementation must ensure that calls to this method and native
focus changes are atomic. If this is not guaranteed, then the ordering
of the focus request list may be incorrect, leading to errors in the
type-ahead mechanism. Typically this is accomplished by only calling
this function from the native event pumping thread, or by holding a
global, native lock during invocation.