Add day (or some minimum unit of time) increment/decrement triangles to Dates Tab

[quadrophobiac]

Desired Behaviour (for improvement suggestions only)

at present a user has to manually select a date to page through the timescale of a metric endpoint. Adding some triangle icon shortcuts for this function would really enhance some of the endpoints, such as Multiple Value Pie Chart View and (especially) the GeoData view where the time and space visualisation is a big selling point of the endpoint