QMII often stumble over her own words - at least when the show is on. - Perhaps it's shyness? She used to be shy and very insecure.
I think she's simply getting older. But she sure has begun to walk unsteadily within the past year or so.
According to the DRF website, the custom started back i 1841 and from 1916 239 window panes with signatures have been registered.
The oldest signature is from 1841 and that is the signature of Louise of Hessen.
This signature is assumed to be of Harry - the future King of Norway:
https://kejserensvilla.files.wordpress.com/2011/07/dsc08871.jpg
This is Georgie, the future King George of Britain:
https://kejserensvilla.files.wordpress.com/2011/07/dsc08873.jpg
But it's not only the windows. The door frames have royal graffiti.
QMII spoke vividly about it in the documentary about the royal palaces.