How to use Indicator count and how to turn key event into code in MQL4

External question — Stack Overflow Stack Exchange Author: RobertFT Original post: https://stackoverflow.com/questions/62783672 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I'm just learning to code and have few questions. Can someone tell me please how to do this thing; 1- How to prevent my custom indicator being duplicated on the chart? If it's already on the chart and I will drop it on to the chart again, I want it to detect the first one and abort launching the second one. something like this: but working :) int OnInit() { int indicators_total = ChartIndicatorsTotal(0,0); for(int i = 0; ndicators_total > i; i++) { if(ChartIndicatorName(0,0,i)==IndicatorName) return(INIT_FAILED); (AND THEN EXIT) } } 2 - How do I detect if there is more than one indicator with the same name on the chart? 3 - How to write an "if" statement to do something if indicator "x" is not present (=0) on the chart? Something like this: but working :) if(IndicatorName==0) { Print("INDI ",IndicatorName, " NOT DETECTED"); } 4 - And is there a way to put keyboard event (F11 - full screen) into code? To make my custom indicator be able to detect when full screen is on just like with the "chart scale" ChartGetInteger(0,CHART_SCALEFIX); ?