Use waitFor instead of sleeping.
Remove sleep from the following,

Button, float, int, multicontainer, selection widgets.
Use wait_for_widget in widgets and string widget tests
Fix command mode & popup view bug

Added elements property to PopupView
Unconditionally register $el with keyboard manager

also s/elements/additional_elements
Merge pull request #5014 from jdfreder/widget-popup-keys

Fix command mode & popup view bug
Merge pull request #4952 from jdfreder/widget-tests

Widget test inconsistencies

add wait_for_widget