clearBackgrounds strange behaviour

[glecko]

clearBackgrounds() only cleans the backgrounds of the items in the actual sheet, not in memory (in the items of Table()).

If you do a clearBackgrounds() followed by a commit(), the backgrounds will be restored as in memory the items still have that background set.

I think the method should clear the backgrounds either only in memory, or both in memory and on the sheet, but never only on the sheet.