initiating display of a first content region and a second content region on an editing track;

initiating display of a transition region between the first content region and the second content region, the transition region including portions of the first content region and the second content region overlaid with respect to each other to represent a transition effect to be applied during successive presentation of content associated with the first content region and the second content region;

wherein initiating display of the transition region includes:

displaying a first selection element in a first region of the transition region for purposes of enabling an edit operation associated with the first content region and to indicate a boundary of the first content region;

displaying a second selection element in a second region of the transition region for purposes of enabling an edit operation associated with the second content region and to indicate a boundary of the second content region;

initiating automatic movement of the second selection element with respect to the first selection element on a respective display screen such that the first selection element and the second selection element appear to move an equal amount and in opposite direction with respect to each other during selection and dragging of the first selection element; and

the automatic movement enabling a respective user to modify a size of the transition region between first content associated with the first content region and second content associated with the second content region.