in VFP,form.addObject(any object..) makes the object always invisible by default
then make it visible by : object.visible=.t.
Note that refreshing pages with pageframes is also important.

this code works and must stay in form.init

With Thisform.pf
	For i = 1 To .PageCount
		With   .Pages[i]
			.AddObject("img_back","image")
			With .img_back
				.Stretch=2
				.ZOrder(1)
				.Left = 0
				.Top = 0
				.Height = Thisform.pf.Height
				.Width = Thisform.pf.Width
				.Anchor = 15
				.Picture = "D:\foxprogs\foxbib\images\blueform.png"
				.Visible=.T.  &&important
			Endwith
			.Refresh
		Endwith
	Next
Endwith