Custom Indicator - Histogram on main chart inside rectangular area defined with click/drag of mouse

 

Hi there.  


I want to write myself a custom indicator which displays a histogram on the main chart that uses price/time parameters defined by clicking and dragging a rectangular area on the chart.  The user would click and drag an area of interest on the chart, and when the mouse button is released, the histogram will be displayed using price/time parameters defined by the rectangular area drawn on the chart by the user.

I have programming experience but I'm fairly new to MQL5.  I have already written myself a couple of indicators.  

I was just hoping for someone more experienced than me to describe to me the language components I can use to best implement this and I'll work out the rest myself.  

Is there already a similar example somewhere?  I did have a look and couldn't find one.

Many thanks.

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