Once your iPad is connected to an output device (e.g. TV or projector), what you see in the preview area of TrialPad will exactly match the aspect ratio of the output device. For example, if you have a television that has a widescreen 16:9 aspect ratio, it has to be displayed inside TrialPad's preview screen, which is a more square shape. The result is that a widescreen fits into the square shape with extra space above and below the live area.
You may have seen a similar issue when an old television show with a 4:3 aspect ratio is shown on a new widescreen television. The result in that situation is gray bars on the sides. To fill the screen the image would have to be stretched, and therefore distorted, and we don't want to do this in TrialPad. For details, please refer to: http://en.wikipedia.org/wiki/Display_resolution
To deal with this issue, TrialPad allows you to collapse/hide the document list to have a larger preview area by pressing the Sidebar button at the top left corner of the screen. Hiding and showing the document list during a presentation does not affect what the audience sees.