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I have the developer guide but it doesn't go into depth on financial charts customization. How can I make a chart that looks like this...
with a shape/annotation/icon/text that floats (either just above or below the main timeseries stock price dataplot) indicating a buy or sell signal? Anyone with sample code or what classes I need to use and how to do that floating H/B icon or that floating rectangle shape? Thanks...

We use Annotations to indicate stock splits and suspicious (interpolated for example) values.
You could easily use them to indicate other things as well.