[Lazarus] ptInRect question

[dmitry boyarintsev]

> I found this out already, but why, what is the rationale ?

i have only one thought, about the reason for this:

if you follow the Microsoft GDI rules, then you'll get
width := r.Right - r.Left;

otherwise (if r.Right is also filled then drawn), you'll end-up with
additional operation
width := r.Right - r.Left + 1;