ohel

Question

Can one open and close a patio table umbrella on shabbat. I think it should be ok because you never really close it completely and there already is a tephach, so you are just adding. Is that correct? 2)a while ago you said you can shut the gas stove on yom tov. Is this similar to rambam where he says on yom tov you can not take the oil out of a candle but you can take away the wood that has not taken hold of the fire. Is the stove issue similar to the wood? or are these two cases not similar? Thanks Gmar Tov