1. Open a qml file containing a Text item in Designer.
2. Select the Text item.
3. Press F1.
   The help page about the Text item is being shown.
4. Go back to Design mode.
5. Set Focus to the Text item's Text property in Properties editor.
6. Press F1.
   You'll see: "QML.Text No documentation available."

Creator should show documentation about the Text item's text property. If this is not possible for a valid reason, it should at least show the documentation about the Text item in general.