And as I promised, here is the tip for making a zipper flap (I'm not sure if this is the correct term in English) to your knitwear (jacket/west or bag, without having the wrong side looking ugly when the zipper is open:
On the side of the knitwear where you want to sew the zipper, with the RS facing, and with two strands of yarn, pick up the desired sts and work as following:
From the two strands of each st on the needle, slip the one (pass to the right needle with yarn in the front as if to purl) and k the next (see photos):
Next row: turn and k every st that was slipped in the previous row and sl every st that was knitted in the previous row. Continue working this way for 3 rows (6 rows). Take another needle and divide the sts as following: every knitted st from last row to one needle, every sl to the other needle.
Bind off. Now you have a "pocket", inside of which you will sew the zipper: