[NumLock]

в переводе с олбанского "следю" означает "next". у TForm также есть метод:

Next method (TForm)
Activates the next child form in the form sequence.
Delphi syntax:
procedure Next;
Description

Use Next to change the active child form of an MDI parent. For example, if you have three child forms within a parent form and Form2 is the active form, the Next method makes Form3 the active form. Calling Next again makes Form4 active. The next time your application calls Next, the sequence starts over again and Form2 becomes the active form once again.

The Next method applies only to forms that are MDI parent forms (have a FormStyle property value of fsMDIForm).