Fix typo

Signed-off-by: Thanh Ha <thanh.ha@alumni.carleton.ca>
Fix #340 Left clicking systray causes Freeseer to minimize

Clicking the systray was always hiding the window. This feature seems
unnatural instead Freeseer will now display the menu on left click.

Signed-off-by: Thanh Ha <thanh.ha@alumni.carleton.ca>