Adding the touchend event listener through the HTML DOM within Amazon Sumerian.
|// Add an event listener for touch events anywhere on the screen.|
|// Note: the MouseUpAction of Sumerian doesn't provide the coordinates|
|// -> use the HTML DOM event directly. This is accessible through|
|// the Renderer.|
|// Phones use touch events. To also develop / test on a PC (or on|
|// a mobile device with a mouse attached), you can also register for|
|// mouse events.|