So what is the problem?
Looks like it is doing exactly what it should be..?
If you don't want your form to follow the center position of the parent then use another approach maybe?
There are apps that intentionally move a form off the top or bottom of the screen but keep it active, if you are
purposing to change this ability then you'll be introducing more issues rather then simply using the provided
code to make your app do as you wish.
Like I said, its best to use existing functionality to make your app do as you wish, but it may not be what
others want to get pushed to do..
If it was something that had no recourse with provided code in the LCL then I would fully agree to fix it..
P.S.
I think the LCL is overly larded as it is and some of it should go on a diet especially in the TFORM area.
Just my opinion.