Event_action_layer_pushed

[circonian]

EVENT_ACTION_LAYER_POPPED (integer eventCode, integer layerIndex, integer activeLayerIndex)
EVENT_ACTION_LAYER_PUSHED (integer eventCode, integer layerIndex, integer activeLayerIndex)

Then there is a lot of API to find out information about it, below is only a few examples (there is more layer API than this), search the wiki API page for "layer" and just go through looking for the API that gives you the info you need.

GetNumActionLayers()
        Returns: integer actionLayers 
 
    GetActionLayerInfo(integer layerIndex)
        Returns: string layerName, integer numLayerCategories 
 
    GetActionLayerCategoryInfo(integer layerIndex, integer categoryIndex)
        Returns: string categoryName, integer numActions 
 
    GetActionInfo(integer layerIndex, integer categoryIndex, integer actionIndex)
        Returns: string actionName, boolean isRebindable, boolean isHidden