State defines the behaviors of a widget regarding mouse and keyboards events.
State.default
This is the default state of a widget where it can only process mouse motion events.State.highlighted
When the mouse is over a widget, it becomes highlighted and can process any mouse events.State.focused
Once a mouse button has been pressed, the widget becomes active and can process both mouse and keyboard events.State.insensitive
When a widget has become insensitive, it can no more process events of any nature.