Beertje mastered the skill of standing up for a limited time without support in his 11th month. We are quite used to the sight of Beertje releasing his hands and staying upright for a while now.
Since 10 days I notice he's discovered the skill of going sit down somewhere and he's clearly enjoying that new sensation. Stairs, shoeracks, ...anything can be a baby chair apparently. This is something Kabouter has never done so elaborately.