Getting Retina mouse coordinates

[circular]

On Retina displays, the interface coordinates are floating point values. As there are two pixels per unit, pixel coordinates are something like 0, 0.5, 1, 1.5, etc.

In the LCL, mouse coordinates are rounded. So one cannot know exactly which pixel was clicked from the parameter of the mouse events.

Question: how to know the pixel coordinates or the interface float coordinates?