Tested:

On current 6.2.2-SNAPSHOT

Situation:

Using in the detail subApp a $textField with 'row: 3':

Using in the treeview/column of this property the editor:

            location:
              expandRatio: 1.0
              filterComponent:
                 $type: textField
              editable: true
              editor:
                availability:
                  nodes: true
                  properties: false
                field:
                  $type: textField
                  rows: 3

results in this, which is quite ok on first view:

Problems to tweak:

• Major: up and down key does not work. Which is very annoying if really want to update a multi line String
• Field should expand to full size -> alpha value should  be high/overlapping/displaying on top of the rows. So it's not cut off at the top.
• One can not click into the field and set the curser or activate any text, as soon as you click into it, all text gets activated (general problem MGNLUI-6035)