The EditionTabController is for edition.
The following configuration is so unnecessary :

<selection-target-type>^content$</selection-target-type>
<selection-subtarget-type>^form$</selection-subtarget-type>
<selection-subsubtarget-type>^field$</selection-subsubtarget-type>
<selection-subsubsubtarget-type>^node$</selection-subsubsubtarget-type>

On the other side, Edition does not necessarily mean ContentEdition, but the EditorController does it.
We should harmonize those two : we could move those classes to a "Content" package or stop watching for the target "Content", but we should keep in mind that in all cases, most buttons for richtext would only works with contents