Dumbledore hiding.../apparating in Hogwarts?

[finwitch]

No: HPFGUIDX 98213

 >  Caesian:
 >  OotP O.W.L.S. 711
 >  'Now, I haven't heard from Dumbledore lately!' she [Madam 
> Marchbanks] added, peering  
> > around the hall as though hopeful he might suddenly emerge from a 
> broom cupboard. 'No  
> > idea where he is, I suppose?'
> >  'None at all,' said Umbridge ... 'But I daresay the Ministry of 
> Magic will
> >  track him down 
> > soon enough ...'
> >  'I doubt it,' shouted tiny Professor Marchbanks,' not if 
> Dumbledore doesn't  want to be 
> > found!' 
> 

 Finwitch:
 We KNOW - ever since book #1, that Dumbledore is able of 
 making himself invisible *without a cloak*. Harry knows this, and I 
 believe that Professor Marchbanks does, too. Maybe she even noticed 
 an invisible person there (an item bent as if someone was leaning 
onto it or just *feeling* that someone's watching) or at least 
doubted it. 
Marchbanks  was also one who said: 'did things with a wand I had 
never seen before' (just how  old IS she, if it's true that *she* 
graded Albus Dumbledore's OWLs and NEWTs?! Has she, perhaps, a 
connection to N. Flamel and taken a little of his Life Elixir?)
 
 Anyway, I think that Dumbledore may have been in his office, 
 considering how Umbridge couldn't get there! (Dumbledore changed 
the 
 password at some point, I suppose...)
 
 Oh, and just as many times as Hermione says that Hogwarts: a 
History 
 claims you cannot apparate or disapparate into/from Hogwarts - but 
does that necessarily include 
 apparating *within* Hogwarts, as long as you don't leave the 
grounds? (I see the anti-apparating as a shield that can't be passed 
by apparating - it doesn't seem to prevent portkeys or floo, anyway).

I'd suspect that if one needs to learn how to apparate, one could do 
it within the Room of Requirement?
 

  
 Finwitch