The developer who wrote the program has to explicitly enable the feature by setting the "installLocation" parameter in the program's manifest file, an XML document that describes application metadata.
KDE provides support for Listaller through Apper, although distributors need to explicitly enable it using a compile-time switch.
The default x264 preset chooses adequate compatibility for Blu-ray players but it is now possible to choose more complex conversion settings while simply maintaining compatibility by explicitly enabling Blu-ray compatibility mode.
Because these 128-bit registers are additional program states that the operating system must preserve across task switches, they are disabled by default until the operating system explicitly enables them.
However, once in Airplane mode, one can explicitly enable Wi-Fi and/or Bluetooth modes to join and continue to operate over one or both of those networks while the cellular network transceivers remain off.
Unlike in Tiger, however, applications in Leopard can explicitly enable Quartz GL, either for the entire application or just for specific windows.
If the site is really broken, as frankly a lot of sites will be, then you can - but you say, okay, I care about this site, then you explicitly enable cookies only for that domain.
Within the Outlook e-mail client TNEF encoding cannot be explicitly enabled or disabled (except via a registry setting).
Clients and servers must now explicitly enable it.
I was lamenting last week that Microsoft didn't default them to being disabled and then explicitly enabled when you knew that it was a control that should be, that made sense to be invokable by Internet Explorer.