The Playback Cursor

Like most timeline-based apps, Moing should have a playback cursor on the timeline. The Moing timeline would have a "scale" divided in two parts: one with the triangular playback head which can be dragged, and the part below it with the scale markings and time or frame numbers:

Below that would be the normal timeline stuff. When the editor panel is maximized, this scale portion of the timeline would appear at its bottom to make up for the lack of the timeline pane.

The current position of the playback cursor determines the moment in time shown in the editor panel, and thus which target frame changes made will affect (or the time at which a new target frame will be created, if there's not already a target frame for that object at the current position). Besides determining the moment in time currently shown in the editor pane, the position of the cursor also determines the position at which playback or recording starts.

If you hold down shift while dragging the timeline cursor, then it selects a range of time. The entire vertical area of the selected range would be shaded on the timeline, but it'd be most evident on the plain region above the scale. This will limit the duration of playback or recording to just the selection range. Static editing while a range is selected results in a pair of target frames on either end of the range.

Holding down control while dragging the timeline cursor snaps it to the nearest segment boundary, or to nearby target frames if target frames are currently being shown in the timeline.

(Dragging segments while holding control always snaps them to each other's ends.)