The window control is a container control used to hold multiple panel-level controls.
There are several ways in which a window control can be used: normal window, dialog or floating window.
Normal Window
A normal window is docked to the desktop dashboard (e.g. layout designer)
Dialog
A Dialog is a modal Window. While it is displayed, all other UI elements outside the modal window are inactive. You must close the modal Dialog to be able to access other parts of the UI
Floating Window
A floating window (also called a “Sticked” or “pinned” window) always stays in front, even if it does not have focus. 
In the screenshot below the Add new instance container represents the floating window.
Please find below some tutorials on designing a window:
How to Design a Maintenance Screen
For full description of attributes and events of this object please access the Client-Logic API