Provide Ability to Toggle Legend On/Off for the Charts

When monitoring many services, the legend occupies such a large area that the chart becomes squished, and depending the the size of the browser window, the chart elements can become unreadable.  Please provide the ability (including in the Dashboard) to allow one to toggle the legend on/off.  I would also like the capability to have a configuration setting that allows me to set the default display mode of the legend to be on or off...but still allowing to override that default on the fly, turning it on or off as desired. Thanks.