What is Layout Manager and explain the Properties and Methods?

The LayoutManager is the engine behind Flex's measurement and layout strategy. Layout is performed in three phases; commit, measurement, and layout.
The commit phase begins with a call to validateProperties(), which walks through a list (sorted by nesting level) of objects calling each object's validateProperties()method.
The objects in the list are processed by nesting order, with the most deeply nested object accessed first. This can also be referred to as bottom-up inside-out ordering.

The measurement phase begins with a call to validateSize(), which walks through a list (sorted by nesting level) of objects calling each object's validateSize() method to determine if the object has changed in size.

The layout phase begins with a call to the validateDisplayList() method, which walks through a list (reverse sorted by nesting level) of objects calling each object's validateDisplayList() method to request the object to size and position all components contained within it (i.e. its children).

Property of LayoutManager
usePhasedInstantiation : Boolean
A flag that indicates whether the LayoutManager allows screen updates between phases.