I do not understand why everyone is so focused on 'rusting' and getting the rollers wet with these glass sliding doors.
Glass sliding doors are exposed to the elements all the time,so if you don't want them to get wet...then you bettered get them their own umbrella because it's going to rain sooner or later.
The rollers are what the doors use to move,these rollers will flatten after years of repeated use...that's just the way it is.
It will not hurt them to get wet,however sand,dirt and grime are real enemies as this is what causes them to wear,and plain old age.
The more exposed the doors are the more often you should vacuum and clean them.Some doors are on covered pool decks,or balconies.Many are right off the yard.
You cannot get all of the debris away from the rollers in situations like this as the weather stripping that resembles a long brush will trap the dirt around the rollers.THis is where the water comes in.
If you flush the area under the door you will be very surprised at the dirt that rolls out. If you let this sandy dirt remain the rollers are forced to keep rolling through it;which shortens the life span of the rollers.
In answer to the window cleaning question:I use water with a small amount of dish liquid.It works well for me in most situations-even construction window cleaning.I also use squeegees not paper toweling.
However,you will find many window cleaning concoctions that are favored by just as many window cleaners.Experiment to find your favorite.