Two observations when using heat maps. Both can be reproduced with Example "Heat Map - Contour".

1. When switching "Show Fill" between on and off, displayed contour lines are moving, although they should remain unchanged. This appears to be a bug.
2. When turning on "Interpolate image", there are artefacts in the coloring along the borders of the heat map, looking like buckles. Maybe this is due to improper interpolation at the borders.