* Returns the sequence feature colour rendered at the given column position,
* or null if none found. The feature of highest render order (i.e. on top) is
* found, subject to both feature type and feature group being visible, and
- * its colour returned.
+ * its colour returned. This method is suitable when no feature transparency
+ * applied (only the topmost visible feature colour is rendered).
* <p>
* Note this method does not check for a gap in the column so would return the
* colour for features enclosing a gapped column. Check for gap before calling