If a single slide is added to the Slide List the Main Screen View looks like this:

The Status bar shows the Full (Slide) Duration and the Slide Icon displays the Slide Duration. For a single slide the Duration will equal the Full Duration because there is no following slide transition time to take into account - or the following slide transition time is zero.

The corresponding Objects and Animation Screen looks like this:

Adding another slide

Adding a second slide with a 2 second transition time causes a change in the Full Slide Duration. Note that the Slide Duration remains the same.

Objects and Animation View:

The Duration of Slide 1 remains at 5 seconds but because Slide 1 is visible from the beginning of its own transition to the end of the Slide 2 transition (at varying opacities) its Full Duration is now 7 seconds.

Example

Key Frames in Slide 1 are placed at Zero and 7 seconds (7000ms) Key Frames in Slide 2 are placed at 5 seconds (0ms) and 12 seconds (7000ms) Below is a Simulation of two slides in Objects and Animation Screen:

The Timeline View: