Kylix does not support the GNU extensions that the Linux kernel depends on. You are writing intensive numerical code. Kylix has an optimizing compiler, but it doesn't optimize floating-point arithmetic. You have all the free time in the world to spend banging out code. Now you know what Kylix isn't good for.
Applications can be desktop tools, from games to word processors.
They can be database clients, servers, or middle-tier layers. They can be network clients such as email readers, or network servers such as web servers. Click on a component, drop it on a form. Select a component and modify its properties. These features are commonplace, and you can find them in Glade, KDevelop, and other tools, so it's no surprise to find this feature in Kylix.