I also wanted to see the effect of not using black rectangles for the empty time periods. It looks like the use of black areas is better as it provides a continuity, and definition to the timeline.
I also added a title from this slide on. Title is an important piece of information and must be displayed at a prominent place on the screen.
One problem with this display and some of previous displays is that it is difficult to fit the heading on the space provided in the rectangle for the event. At first thought, it would seem like using smaller fonts would solve the problem. Not really ! For some events with small duration, the rectangle width will be really small and no matter how small a font you use it will not fit in the space. Other problems is that, length of the heading is not constrained, so a user can provide a long heading that will not fit in the space. Problem with smaller font is that any font less that 8 point is hardly readbale on the computer screens.
Solution to this problem will be discussed later.