The functionality of the Visualize tab will provide you with a visual representation of market data. Two modes of visualization are available: Heat Map and Index Watch (you can switch between these using the Visualize drop-down).
The Heat Map represents the price activity of symbols in a watch list based on three visual parameters: color, brightness, and area. Red rectangles represent symbols that have moved downward, while green represent those with upward price movement; the brighter the color, the greater the move. The area of each rectangle is proportionate to the company's market cap.
The Index Watch mode provides a visual representation of how the indices of user-defined watch lists are performing intraday.