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Split View in Compositor Using the Drag Handle with Trim

The Trim Feature using the drag handle provides some good ways to view your video while editing. The playback position in the compositor is updated live and the view in the compositor can be split so that in the left half of the compositor you can see the last frame of the left clip and in the right half the first frame of the right clip. Dragging edits can not be extended past the beginning or the end.

First familiarize yourself with button operation; check your setup by executing the following step. In the Settings → Preferences → Interface tab, Editing section, clicking on the edit boundaries can be set for LMB (Button 1), MMB (Button 2), RMB (Button 3) as one of the following:

Ripple; Roll; Slip; Slide; Edge or No effect

Now to use this feature, create a track with edits that have trims on the left and/or the right. The edit boundary can be modified using drag handles at the boundary between the edits (figure 6.6).

Figure 6.6: Split compositor screen showing the result of the Trim feature

Left Mouse Button (LMB) usage:
  If you grab the edit handle from the right side, you will see a left arrow and dragging the boundary will modify the right edit playback starting time. If you grab the edit handle from the left side, you will see a right arrow and dragging the boundary will modify the left edit playback ending time. In both cases, the composer will show the edit endpoint of the changed edit.
Shift LMB usage:
  The effect on the edits is the same as described above, but the composer will show a split screen of the left and right edits as they appear at the drag handle boundary. Dragging will only change one of the two images, since only one edit is being changed.
Middle Mouse Button (MMB) usage:
  Both the left and the right edit ending/starting times are updated. The image shown in the compositor will be drawn from the side of the drag grab, that is the left if it is grabbed from the left, and the right if it is grabbed from the right.
Shift MMB usage:
  The effect on the edits is the same as described above, but the composer will show a split screen of the left and right edits as they appear at the drag handle boundary. Dragging will change both of the two images, since both edits are being changed.
Right Mouse Button (RMB) usage:
  The start/end point of the current edit is moved, but the edit length is unchanged only one image changes since only one edit endpoint is view is updated.
Shift RMB usage:
  The effect on the edits is the same as described above, but the composer will show a split screen of the left and right edits as they appear at the drag handle boundary. Dragging will only change one of the two images, since only one edit is being changed.