uses in implementation?

[Basile B.]

The implementation uses section is used mainly to avoid circular reference, but also for local use files.

You need to study Lazarus units and memorize in which units are which classes. Or you can use a feature in Lazarus to find Identifiers with the mouse right button (right-click on the compiler message "Identifier not found"and choose "Find Identifier").

It's also used in the implementation section to avoid the initialization section of the used unit to be called. It can sometime save a few kBytes in the output program, even if I admit this is rarely used. However it's still good to know that the "static unit constructor" is not called in this case.