Btw, if I select "code librarian" from menu, the window is created partly out of the screen.
This seems to be caused by poMainFormCenter
The main form is the IDE-main-bar (with the menu, and component palette). I don't use anchordocking, and my ide-main-bar is on the top of the screen. Since your form's height is bigger that that of the IDE-main-bar, the code move the new top of your form to be higher than that of the ide-main-bar => and that new top is outside the screen.
---
I have no idea if the current LCL behaviour is any good as it is (or if it should be improved). => new different topic.