Selection with a Magnifier

[lostcpu]

a magnifier is needed when mouse selecting. the current mouse selection is not precise.
it is necessary when zoom is smaller than 20%, and still useful even zoom 100%

suggestion:
option 1.make it default with left click selection
or
option 2.No change for current left click selection, a Magnifier display with right click selection.

Magnifier should automatically decide its own position. for example, magnifier should change it's own display position if mouse is about to move into this field.