The FlexGantt framework supports layers, which behave similar to
layers found in graphic programs (such as Photoshop). A layer allows the
application to group timeline objects together. Layers can be turned on / off,
their alpha channel value can be changed so that they appear translucent, their
ordering can be changed so that timeline objects that were previously hidden by
other objects can be made visible, etc...


Layers are defined as part of the Gantt chart model. Queries to the model for
timeline objects always pass in the layer for which the query gets performed.
This way the model can decide which timeline objects will be placed on which
layer.

