Apologies. When trying to set a simple flow for Colin this did not occur.
On further investigation a previous setting of nrdb-ui-chart.height, was affecting the height of the Group background, and as the widget height is restrained to the number of rows at a fixed height this left a gap between the bottom of the widget and the bottom of the Group. This gap varied according to the number of rows allocated to the chart. (I can no longer get a 3 * 3 chart to fill the space so I have no idea what was going on there)
This will probably not affect many people so this issue can be probably be classed as resolved. Please let me know if you are happy with that.
