Indicator: set Chart on Foreground as default

I have the attached indicator and I need to add the code that will set the "Chart on Foreground" as default. Can someone please post this code?

This indicator will display the EUR & US trading sessions on your chart.

TradingSessionsEUR&US.mq4

if I may, add an issue, I will like your help how to resolve this problem-
for example. Ill take the histogram that is part of the above "trading sessions" indicator:
when we like to shadow a surface with wide histogram lines , the shadow covers other indicators, unless you load it as the 1st indicator, before others, and the Chart was set to foreground.
Now the problem that remains is, that the trading lines (Buy/Sell , and Bid/Ask) are covered by the Histogram.
Is there any way to resolve this issue and have those trading lines on foreground as well?
thanks,