Sort indicator doesn't distinguish between Name and Ext
If you keep clicking the Ext in the Name&Ext column, the sort direction arrow indicator will change direction, but it will stay in the center of the Name&Ext column. Same if you click the Name in the column, even though sorting will be very different whether you've clicked on Name or Ext.
Suggestion: change the x position of the sort direction indicator to the center of the word Name or Ext, depending which was clicked.
This will correctly reflect the sort criterion in addition to the sort direction.