Any way to stop timeline space from moving?

Hi,
When I use the mouse to try to circle and highlight a group of clips I almost invariably end up moving the timeline space down in the process, obscuring video clips below the line separating them from audio. This happens as soon as I click on the mouse and begin to move it and before I am able to highlight those clips. Is there any way to restrict the adjustment of the timeline video space to the little verticle bar designed for that purpose on the right end of the timeline?
Thanks.
John
When I use the mouse to try to circle and highlight a group of clips I almost invariably end up moving the timeline space down in the process, obscuring video clips below the line separating them from audio. This happens as soon as I click on the mouse and begin to move it and before I am able to highlight those clips. Is there any way to restrict the adjustment of the timeline video space to the little verticle bar designed for that purpose on the right end of the timeline?
Thanks.
John