Syntax Highlight Not Available in Eclipse Plugin

I associated the .ext extension with Oxygen in Eclipse. Why does an .ext file opened with the Oxygen plugin not have syntax highlight?

Associating an extension with Oxygen in Eclipse 3.6+ requires three steps:

  1. Associate the .ext extension with the Oxygen plugin.
    1. Go to menu Windows > Preferences > General > Editors > File Associations .
    2. Add *.ext to the list of file types.
    3. Select *.ext in the list by clicking on it.
    4. Add Oxygen XML Editor to the list of Associated editors and make it the default editor.
  2. Associate the .ext extension with the Oxygen XML content type.
    1. Go to menu Windows > Preferences > General > Content Types .
    2. Add *.ext to the File associations list for the Text > XML > oXygen XML content type.
  3. Press the OK button in the Eclipse preferences dialog.
Now when an *.ext file is opened the icon of the editor and the syntax highlight should be the same as for XML files opened with the Oxygen plugin.