The FloatLayout class will just honor the Widget.pos_hint and Widget.size_hint attributes.
For example, if you create a FloatLayout with size of (300, 300):
layout = FloatLayout(size=(300, 300))
# by default, all widgets have size_hint=(1, 1)
# So this button will have the same size as layout
button = Button(text='Hello world')
layout.add_widget(button)
# if you want to create a button to be the 50% of the layout width, and 25%
# of the layout height, and set position to 20, 20, you can do
button = Button(text='Hello world', size_hint=(.5, .25), pos=(20, 20))
# If you want to create a button that will always be the size of layout -
# 20% each sides
button = Button(text='Hello world', size_hint=(.6, .6),
pos_hint={'x':.2, 'y':.2})
Note
This layout can be used to start an application. Most of time, you need to want which size is your Window.
Warning
If you are not using pos_hint, you must handle yourself the position of your childs. Mean if the float layout is moving, your must handle the moving childs too.
Bases: kivy.uix.layout.Layout
Float layout class. See module documentation for more informations.
Calculates the minimum size of the layout.