+ /**
+ * Edits the sequence to insert or delete one or more gaps, in response to a
+ * mouse drag or cursor mode command. The number of inserts/deletes may be
+ * specified with the cursor command, or else depends on the mouse event
+ * (normally one column, but potentially more for a fast mouse drag).
+ * <p>
+ * Delete gaps is limited to the number of gaps left of the cursor position
+ * (mouse drag), or at or right of the cursor position (cursor mode).
+ * <p>
+ * In group editing mode (Ctrl or Cmd down), the edit acts on all sequences in
+ * the current selection group.
+ * <p>
+ * In locked editing mode (with a selection group present), inserts/deletions
+ * within the selection group are limited to its boundaries (and edits outside
+ * the group stop at its border).
+ *
+ * @param insertGap
+ * true to insert gaps, false to delete gaps
+ * @param editSeq
+ * (unused parameter)
+ * @param startres
+ * the column at which to perform the action; the number of columns
+ * affected depends on <code>this.lastres</code> (cursor position)
+ */