Automatic detection of indicator styles


In MetaTrader 4 the styles (e.g. arrows or lines) that are used in an indicator are not chart objects.  ObjectsTotal()  returns 0. Of course I can read this out via  iCustom() . But what, if the EA should react to all indicators with such symbols. So without knowing the number of buffers and/or the settings of the indicator?

I have seen an indicator which opens a GUI with a selection of other indicators that are currently also in the chart (only those with arrows and dots, no indicators only with lines). If you select an indicator, you will be offered the styles (for example green arrow), including the buffer number. You can then specify that this should be a buy signal, for example. This indicator automatically recognizes arrows and points from other indicators in the chart, including the buffer number and color. 

Does anyone know how this is possible? Or can I read out from EA the information in the data window?