Tree Editor allows text in element-only elements
If you click, "Show All" in Morpho, the expansion of the EML is truncated at some point for performance reasons. However, there is no indication where this truncation has occurred, and users are allowed to enter text into elements which should only contain other elements, since they appear as leaf nodes. This ends up with the user unknowingly generating invalid EML. Morpho needs to prevent users from being able to enter text in elements that should only contain other elements.