Dragged zoom is active only when the left mouse click is in zoom mode, that is, when the magnifying glass button is pressed in the toggled buttons as in Figure 3.11. In zoom mode, the cursor within the canvas will appear like a magnifying glass with a plus sign in the center, as in Figure 3.13. It is called the zoom-plus cursor. The dragged zoom operation is initialized by pressing the left mouse button at the beginning of the zoomed-in region; a white line will then appear. As soon as dragging is detected, another white line will appear to mark the current ending of the zoomed-in region. The region that is marked by the pair of white lines is lightly shaded, as shown in Figure 2.4. The process can be canceled by hitting the ESC key during dragging. Once the left mouse button is released, zooming will be carried out, and the Timeline window will then be updated as in Figure 2.5. The time display panel is updated with the latest time-related information of the zoomed-in region. Notice that zooming as well as scrolling can be achieved by explicitly editing the text fields in the time display panel.
