------ Controls
Control Widget is kivy basic elements of the graphical interface. Control provides a canvas Canvas , which is used to draw on the screen. Controls receive events and respond to events.
A control's child controls will be children attribute expressions, this property is a kivy the list of attributes ListProperty . The following methods can be used to operate the control tree:
· Add_widget () : Adds a control as a child control
· Remove_widget () : remove a control from child control list
· Clear_widget ( ): Empty a control of all the child controls.
Control Index: drawing order control, is obtained based on the respective control positions in the control tree. Add the specified location in the control of the control tree method: root.add_widget (the widget, index)
Note: The index of small value of the control will be drawn on top of large index value control, the default value is 0
------ finishing layout