Arc
Application
Allows the user to draw an arc on a chart. A common use case for this feature is highlighting patterns on a chart, for example the cup and handle chart pattern.
Style
In the Style property dialog, it is possible to change the appearance of an arc:
Border
Sets the color and thickness of an arc border.
Background
Toggles the visibility, color and opacity level of an arc background.
Visibility
In the Visibility properties dialog, you can switch the Arc tool displaying on charts of different timeframes: