Dragall detect different kinds of user actions. The visual feedback of these buttons can be controlled by using different kinds of
shows how to implement a check box using
There are three kinds of margin feedback,
so there are three constructors
The first one will cause a check box to be displayed, the second one
will display a check mark,
and the third will display a bullet.
Their children are usually a TextVBT that displays a label for the item.
Checkbox a checkbox is created using
Its child is a
And its child is the text for the label.
The checkbox is a child of a
which in turn is a child of a switch VBT,
which in turn is a child of
The boolean VBT maintains the on/off state of the switch.
When the state is changed (by pressing the button)
a callback is invoked.
In the program
Check is called
which changes the label of the button for ``Check'' to ``Uncheck''
Four views of the application are shown in the following images: