this is if you use two LCD screen
When you use SetOwner the second form open over Mainform but if you move mainform to another LCD
the addnew open in Default LCD not over the Mainform
You can use this code to show the child form in the center:
B4X:
Sub MainForm_MouseClicked (EventData As MouseEvent)
Dim frm2 As Form
frm2.Initialize("frm2", 500, 500)
frm2.Show
SetFormInCenter(MainForm, frm2)
End Sub
Sub SetFormInCenter(Parent As Form, Form As Form)
Form.WindowTop = Parent.WindowTop + (Parent.WindowHeight - Form.WindowHeight) / 2
Form.WindowLeft = Parent.WindowLeft + (Parent.WindowWidth - Form.WindowWidth) / 2
End Sub