Head rail of window covering and lid fastener

A head rail of a window covering, comprising:

• a rail member having an open end and at least two protrusions on the lower bottom corners thereof;
• a rail lid engaging the open end of the rail member;
• and
• a lid fastener engaging the rail member so as to secure the rail lid to the open end of the rail member, wherein the lid fastener comprises:
• a main plate;
• two clip plates connected to opposite ends of the main plate, the clip plates being secured to the at least two protrusions on the lower bottom of the rail member wherein an acute angle is between each of the clip plates and the main plate and engages the rail lid;
• at least one stop plate between the clip plates on the main plate where the stop plate is provided on an edge of the main plate, wherein opposite ends of the edge are connected to the ends connected to the clip plates respectively;
• a curved portion formed at a middle of said main plate so that when said curved portion is pressed said clip plates bend outward and where said clip plates and said stop plate are projected from said main plate in the same direction;
• said curved portion of said main plate is projected in a direction opposite to said clip plates and said stop plate;
• and
• an extending plate that is connected to a free end of said clip plate wherein said clip plate is bent inwards, and said extending plate is bent outwards.