Python qt: docks

NOTE:

Docks can only be parented to QMainWindow subclasses.

## Build QMainWindow
win    = QtGui.QMainWindow( parent=newUI.getMaya() ) ## MUST BE QMainWindow
layout = QtGui.QVBoxLayout()
win.setAttribute(QtCore.Qt.WA_DeleteOnClose)
win.setLayout( layout )


## Build Dock
dock = QtGui.QDockWidget( 'MyDock', parent=win )		## Dock Widgets REQUIRE a parent so they do not
																		#  get garbage collected prematurely.
dock.setAllowedAreas( QtCore.Qt.LeftDockWidgetArea | QtCore.Qt.RightDockWidgetArea )
win.addDockWidget( QtCore.Qt.RightDockWidgetArea, dock )

btn = QtGui.QPushButton( 'Dock Contents' )
dock.setWidget( btn )