Hide several task rows in a single operation

Answer:

Yes.  Follow these steps for rows which are non-contiguous.

1. Click  (the arrow tool.)
2. Hold down the CTRL key.
3. In the column area, click the first row to be hidden.
4. While holding down the CTRL key, continue selecting rows to be hidden.
5. Click the Hide button on the toolbar.   

Follow these steps for rows which are contiguous (together.)

1. Click  (the arrow tool.)
2. Hold down the SHIFT key.
3. In the column area, click the first row to be hidden.
4. While holding down the SHIFT  key, click the last row to be hidden.
5. Click the Hide button on the toolbar, or choose Hide tasks on the right-click menu.