Hey babydust,
cuetip is right. A hob scraper, marvellous for all uses, grease/marks off tiles/HOBS/ovens, paint of windows mirrors/glass etc...sticky labels of jars/glass/mirrors, the list is endless, and as cuetip says, it does not scratch or mark the surface...
We have a georgian door (sitting room) 15 glass panels, and when we decorated, unlike my hubby - I'm not good at cutting in - so the scraper was invaluable to getting the line of paint in each panel (separated by wood)...
n00dles