Remove the border for selected text-elements
Fix lint-errors
Don't use controls as relative root elements

Prepending might be deferred, and if it is, the control is likely to
have disappeared by the time the element is to be inserted.

Therefore, only use content- or column-elements as relative roots.
Implement adding widgets as content
Move widget tooltips to new button-elements
Add tooltip to add-content rows
Trigger mouseout when selecting content
Add edit-structure button tooltips
Show/hide tooltips appropriately
Redesign the remove-content icon, add tooltip
Confirm removal of content
Remove unused code, reorder and clean up
Exclude remove-content from hover-opacity
Use slightly lighter backgrounds
Use consistent phrasing
Set max-width on iframe-placeholder
Remove margin-fix, not needed without hover-borders