4.3.2 Information Mural The main purpose of the Information Mural is to provide a visualization overview that relates sections to topics to time. This has been achieved by placing topics on the vertical axis, ordered by time from top to bottom, and placing a small box in place for each slide on the horizontal axis, again ordered by time from left to right. For a class in which topics were discussed strictly going forward, i.e. without back-referencing, the Information Mural would yield a diagonal line. However, if the class material jumps back and forth between topics, then this behavior would stand out in the Information Mural by gaps in the diagonal.	Figure 11: Information Mural representing continuous topics versus Figure 12: Information Mural representing dis-continuous topics
Similar to the Slide Frame, a color strip displays the media types for each topic. When clicking inside the color strip, the associated topic is selected in all frames. Besides offering a visualization method, this frame also allows the user to play back all selected slides over time. While playing back a collection of selected slides, the original image data is displayed in the Image Frame. Furthermore, both the Slide Frame as well as the Information Mural display the current slide's location by means of transparent bars, as already discussed above.	Figure 13: Information Mural during Playback
The control buttons for playback have assumed generic symbols. From left to right: Play reverse, Play forward, Pause, Rewind, Skip to last slide, Next slide, Previous slide. The last two buttons can be used to either speed up a playing film strip, or browse through the selected slides while in Pause.
Figure 14: Playback controls