Astor Main Window
On the main window, the control system is displayed as a tree.
Where the root is TANGO, the branch are hosts family and leaf are hosts.
The Astor main window is able to give a global status of the control system.
The tree is collapsed, but the node icon display the status of the hosts under.
An individual control on a host could be done by a click on a host.
A popup menu will be displayed with a right click on a host.