As purveyors of sunlight and, with luck, reasonable views, windows have more clout than any other feature when it comes to styling your interior.
Their size, shape and style do pose some boundaries but the way you choose to dress - or undress - them sets the tone of a room, says interior designer Angela Hall.
'Very often, windows serve as the focal point of a room, for example in a more traditional setting or if there is a great view,' she says.
'But ... the more windows there are, the more difficult it can be to pull off a comprehensive window treatment because you don't want it taking over the entire room. Once you have dealt with the practical considerations - keeping out light, heat, prying eyes and so on - you have to decide if you want the window treatments to be an interior feature in themselves or to be something that doesn't distract from what's important, whether that's the great view or the rest of the interior space.'
Another factor is technology. Ivan Chau of Tea Interior Design says hi-tech materials and manufacturing processes are shaping trends despite, or perhaps because of, their high costs.
'Take window frames, for instance. Very thin 'barely there' window frames are really in demand now, even though they have to be custom made and cost three times as much as regular frames. And glass technology has also become very advanced in the past few years, bringing some new trends into window treatments like liquid crystal 'privacy glass', which turns black at the flick of a switch.'
With the glass alone costing about eight times that of standard glass, privacy windows are used sparingly. They are most popular in bathrooms and boardrooms.
Hiris Tam of Bellavista Concepts, which supplies window blinds and shades by Hunter Douglas, a self-styled 'window fashions' company, claims an edge over competitors with details like dust-resistant fabric (with a lifetime guarantee) and child-safe retractable cords but more Hongkongers are enjoying the 'fashion aspect' of their decision. 'Although white and off-white have always dominated the market, recently accent colours like bright red and purple have become more popular, with many young people choosing black,' she says.
Hunter Douglas has launched Alustra, a range of fabrics in gold and silver weaves. According to Hall, that is opportune. 'Metallic fabrics are a very popular trend right now,' she says. 'Either open weave or closed with a UV backing - the fabrics are very lightweight but the metallic sheen gives them an added dimension. Earthier metals like pewter, gunmetal and bronze are also very fashionable right now.'
Curtains may not offer as many hi-tech options but the colours, patterns and textures available are boundless. The main fabric panels may be embellished with more fabric in a surprisingly wide array of possible configurations: swags and jabots, cornices and valances, and sometimes further layers of draperies or sheers, not to mention sashes and tassels and all the hardware: rods, knobs and finials (decorative alternatives to knobs).
Easier and generally cheaper to make and install, curtains are more popular than blinds but complex multilayered ones are not for everyone. In minimalist interiors, barely-there sheers or slim-line horizontal blinds that disappear into the window frame are more in keeping with pared back surroundings.
Similar to privacy glass, another uncluttered approach is to treat the windowpane itself. Frosting the lower half of a double-hung window has two benefits - it can obscure unpleasant views as well as maintain privacy, both without sacrificing light. Frosting or etching glass can be pricey work but an inexpensive alternative is adhesive window films, such as those by Britain's Emma Jeffs, whose floral and geometric designs, once applied, mimic the effect of acid-etched glass, providing a subtly decorative window treatment.
Frosted glass and barely there sheers are all very well in areas where too much light is not an issue but, for many, blackout shades or curtains in the bedroom are a must for a good night's sleep. New parents are often advised that a pitch-black nursery is the surest route to helping their babies sleep through the night. Most adults (except new parents perhaps) also have difficulty with sleeping if there is more than a hint of daylight. Many people assume this means heavy fabrics or thick blackout linings are essential, traditionally making window treatments in the bedroom heavier and darker than in the rest of the home, but these days much lighter alternatives are available.
According to Carmen Lee, senior sales and marketing officer at Hunter Douglas, 'For our Hong Kong customers one of the highest priorities is the shade's ability to block out sunlight and harmful UV rays.' The company's Silhouette range remains a popular choice for bedrooms because of its ability to close almost completely flat and block out light. Made from a combination of sheer and opaque ultra-lightweight fabrics available in more than 300 colours and finishes, Silhouette works like a kind of fabric double-fronted venetian blind and can allow in varying levels of light while keeping the window covered - for UV protection as well as privacy.
But what if you prefer to go naked? Where privacy and daytime light control are not priorities, keeping a window undressed is the simplest treatment of all. 'It wouldn't be my preference,' says Hall, 'but naked windows might provide the best match for a starkly minimalist interior. Or maybe if the window was especially beautiful or well-made, keeping it bare would be one way to emphasise that.'
One champion of the undressed look is Ardyn Thompson, a mother to three small children, all of whom regularly slept through the night at an enviably early stage despite a conspicuous lack of blackout curtains in their rooms.
Indeed, the tall colonial-style windows are completely unfettered by rods or coverings of any kind so that during the day the elegantly furnished rooms are always bathed in sunlight.
Her secret? Come bedtime, Thompson flicks a switch and external typhoon shutters crank into position, creating a total blackout environment for her children with which even award-winning custom shades can't compete.