Layouts
--------

Layouts are containers used to arrange widgets in a particular manner::

    AnchorLayout:   Widgets can be anchored to the 'top', 'bottom', 'left',
                    'right' or 'center'.
    BoxLayout:      Widgets are arranged sequentially, in either a 'vertical'
                    or a 'horizontal' orientation.
    FloatLayout:    Widgets are essentially unrestricted.
    RelativeLayout: Child widgets are positioned relative to the layout.
    GridLayout:     Widgets are arranged in a grid defined by the `rows` and
                    `cols` properties.
    StackLayout:    Widgets are stacked in a `lr-tb` (left to right then top to
                    bottom) or `tb-lr` order.

When you add a widget to a layout, the following properties are used to
determine the widget's size and position, depending on the type of layout:

    **size_hint**: defines the size of a widget in its parent space as a percentage.
    Values are restricted to the range 0.0 - 1.0 i.e. 0.01 = 1% and 1. = 100%.

    **pos_hint**: is used to place the widget relative to the parent.

The **size_hint** and **pos_hint** are used to calculate a widget's size and
position only if the value(s) are not set to ``None``. If you set these values to
``None``, the layout will not position/size the widget and you can specify the
values (x, y, width, height) directly in screen coordinates.

For a detailed look at how you can arrange widgets using layouts, please refer
to:

- :mod:`AnchorLayout <kivy.uix.anchorlayout>`
- :mod:`BoxLayout <kivy.uix.boxlayout>`
- :mod:`FloatLayout <kivy.uix.floatlayout>`
- :mod:`GridLayout <kivy.uix.gridlayout>`
- :mod:`StackLayout <kivy.uix.stacklayout>`
- :mod:`RelativeLayout <kivy.uix.relativelayout>`