Not all baby/pet gates come with a stay-open feature and the ones that do don't always work that well. It's a pain when the kid is napping and you're going back and forth carrying laundry and dishes. Anyway, here is a simple way to hack your auto-close baby gate to stay open when you want it too.
Find a standard auto close baby gate that annoys you daily.
Find or buy a short bungee cord about 2 feet (60cm) or less. If your gate is extra wide, you may need a longer bungee. This is for a standard door-width gate. For additional safety, you might want to find bungee cords that don't have exposed metal on the hooks. Otherwise, some duct tape can cover it up.
Wrap the bungee cord around (approximately) six bars of the gate starting with the first bar on the side with the hinge. Stretch the cord until it is tight and hook the ends of the bungee cord together. When the gate is in the closed position, the cord should be taut. If it is too loose, you may need to wrap it around more than six bars. (Or use a shorter cord.)
If the hooks of the cord are exposed metal and you are worried about a kid getting hurt, you can wrap the exposed ends with some duct tape at this point. Otherwise, your gate will now stay propped open when you need it too.