Add first prototype of new content insertion
Enable inserting images
Implement simple column-count toggling
Implement removing content
Append extra content, not prepend
Reset add-content buttons on change, avoid state
Reset all controls together
Insert after, not before, given element
Let caller choose insertion method
Insert new row if column-count differs
Prepend to column, not its children
Remove empty rows on reset
Add sidebar-left column layout
Remove obsolete statements
Add icons for structural changes
Add template snippet
Select previous row correctly
Adjust remove-content overlay size
Select more specifically
Stop click-propagation when removing content