This method can be used to insert a new page into a register group. The new page specified
by "obj" must be a detached group object. This detached group object will then
be inserted into the register position specified by "pos". This is an integer
position starting from 0 for the first page. After this method returns the specified group
object will change its state from detached to attached. That is why you must no
longer use functions that expect a detached object with this object now.
Detached MUI objects can be created either by calling the mui.CreateObject()
function or by explicitly detaching them from their parent by using the
This feature requires at least MUI 4.0.