Flashing cells briefly appear when cell values' change.
By default they flash for half a second, with a green flash for a positive change and a red flash for a negative change but this can be amended by you.
This (very contrived!) example has 4 Flashing cell columns: The 'Item Cost', 'Order Cost', 'Change Last Order' columns use the default flashing values while (for no particularly good reason) the 'Invoiced' column has different colours and a longer duration.
The Dashobard has been put into floating mode - useful for when screen estate is at a premium.