Allow null items in context menus
Add list in costumes tab
Implement textLayer loading and fix costume list updating
Fix default new sprite costumes
Add layoutChildren call in wrap-drop

Technically this isn't necessary, but it's the only case of block nesting changes where layoutChildren isn't called. Adding this call allows easy implementation of zebra coloring, among other things
Remove editor stepping

If its children need to poll something, they can do it using the interpreter's step or their own setInterval call.
Remove some resize() calls/implementations
Fix mouse coordinates in small stage mode
Fix layout in small stage mode
Fix objectFromPoint in small stage layout
Show watchers when creating lists