Compared to an open backyard, barbecuing accidents have greater implications in an apartment block. Before buying a whiz-bang new gas BBQ for your balcony, check the by-laws for your complex and/or the owners' corporation (previously called the body corporate) to see if there are any restrictions on using a gas BBQ on your balcony.
For safety reasons, gas barbecues must always be used in very well ventilated space. Barbecuing in an enclosed balcony is not advisable – even those with louvres, café blinds, or a significant amount of privacy screening could be a very risky venture.
If this is your scenario, consider an electric barbecue.