(before container)
(after container)
button1
focus
button2
button1
focus
button2
button1
focus
button2
button1
focus
button2
button1
will be removed
focus
button2
button1
focus
will be removed
button2
button1
focus
will be moved
button2
button3
button4
button1
will be moved
focus
button2
button3
button4
button1
parent
focus
button2
button1
focus
button2
button1
button2
button3
button1
button2
button3
button 1
focus
button 5
button 2
button 4