The Object Browser is not explicit about having to create SIZE objects, it says that the Width and Height objects take integers, which is not entirely true. This is some sample code which I use to unlock the size of a minimizable form:
Dim min As Size
Dim max As Size
min.Width = 0
min.Height = 0
max.Width = 0
max.Height = 0
Me.MinimumSize = min
Me.MaximumSize = max