Extract a module ViewMode.
Remove a reference not need.
Rename a variable viewModel to buttonController.
Move the viewMode from the view to the editor.
Move the TypeStyle from the viewMode to the view.
Extract a module ObservableValue.
Make typeGap ObservableValue.
Disable the boundary-detection button at the view-mode.
Extract a module GridRenderer.
Refactor the module SpanRenderer.
1. Extract a module RenderSingleSpan.
2. Extract a module getFirstTextNode.
3. Extract a module createSpanRange.
4. Fix indent.
Split a css class of the block span.