MB4 204b: Extending a Scroll from one Domain to Another on Shabbos (352:1-2)
If a person is holding a scroll in Reshut HaYachid and it rolls into Reshut HaRabim one can bring it back into Reshut HaYachid.
Reading from a scroll on a roof and one end rolls but stops more than ten tefachim from the ground (מקום פטור). What if the roof is slanted?
If the scroll is כתבי הקודש and it stops within 10 tefachim but doesn't touch the ground he can bring it back because of בזיון כתבי הקודש, otherwise Chazal made a גזירה against doing so.