Clicks map to wrong line with line-spacing > nil.

[David Koppelman]

Mouse clicks map to the wrong line on recent versions (including
8a7a99) when line-spacing is set to a non-default value. For
example, set

(setq-default line-spacing 10)

and try clicking on a line towards the bottom of the window. The
cursor moves to a point well above the mouse pointer.

Am I the only one setting this variable? Or is there something unusual
about my system? (RHEL 6.)

David