Event.current.MousePosition shows the jumping x axis values. This is happens while dragging the object in the Scene window.

Reproduction steps:
1. Open the attached file;
2. Open MainScene;
3. Select object 'UnitCircle' in the Scene window;
4. Slowly drag it from top to bottom and observe Console window where is written MousePosition values;

Actual result: When you drag the object slowly along y axis, you can see that mouse position of x axis values jumps between big different values (e.g.: from 327 to 756)
Expected result: The mouse position of x axis value shouldn't jump between big difference numbers while dragging the object along y axis. It's should be almost the same value if you drag straight.

Workaround: The issue disappears when in the Inspector window (of the object 'UnitCircle') you close the Transform tab. It's strange but than mouse position of x axis doesn't jump and shows correct values. Also the problem is just with x axis. When I repeated the sames steps along x axis, y axis values were correct.

Reproduced on Unity 5.5.0b8, 5.5.0b5, 5.4.1f1.
Tested for regression with Unity 5.3.6p4, 5.2.5f1.