The circle tool (ellipsis PLUS Shift key) has lost much of its usefulness: Many times I need to draw a circle, centered on a vertical or horizontal line. Previously, I simply ran the mouse down the line with the Shift Key held down and that's it. In 4.0.5, I have to move the mouse diagonally and the "upper left corner of the circle" is fixed. If this has any advantages, I have still to discover that. Please return to the old behaviour!
Or perhaps there is a hidden option switch somewhere that I have overlooked?