code: function _getIntersectingLayer(data) {
  	var layer, i,
  		mask, m;
  
  	// Store the topmost layer
  	layer = null;
  
  	// Get the topmost layer whose visible area intersects event coordinates
  	for (i = data.intersecting.length - 1; i >= 0; i -= 1) {
  
  		// Get current layer
  		layer = data.intersecting[i];
  
  		// If layer has previous masks
  		if (layer._masks) {
  
  			// Search previous masks to ensure
  			// layer is visible at event coordinates
  			for (m = layer._masks.length - 1; m >= 0; m -= 1) {
  				mask = layer._masks[m];
  				// If mask does not intersect event coordinates
  				if (!mask.intersects) {
  					// Indicate that the mask does not
  					// intersect event coordinates
  					layer.intersects = false;
  					// Stop searching previous masks
  					break;
  				}
  
  			}
  
  			// If event coordinates intersect all previous masks
  			// and layer is not intangible
  			if (layer.intersects && !layer.intangible) {
  				// Stop searching for topmost layer
  				break;
  			}
  
  		}
  
  	}
  	// If resulting layer is intangible
  	if (layer && layer.intangible) {
  		// Cursor does not intersect this layer
  		layer = null;
  	}
  	return layer;
  }
docs: Get topmost layer that intersects with event coordinates