Fastening system and window shade including the same

A fastening system for a window shade, comprising:

• a first clipping element having a first latching part, wherein the first latching part is a protruding structure that is provided at a first location on the first clipping element and has a first engagement portion and a second engagement portion;
• and
• a second clipping element having a second latching part operable to engage with the first latching part for attaching the second clipping element to the first clipping element, wherein the second latching part is another protruding structure provided at a second location on the second clipping element, the first and second clipping element being attachable to each other for holding at least one panel of a window shade in a gap between the first and second clipping element;
• wherein the first clipping element is attachable to the second clipping element according to a first configuration and a second configuration, the gap between the first clipping element and the second clipping element being greater in the first configuration than in the second configuration, the fastening system being configured to hold two panels of a window shade in contact with each other in the gap between the first clipping element and the second clipping element in the first configuration, and the fastening system being configured to hold a single panel of a window shade in the gap between the first clipping element and the second clipping element in the second configuration;
• and
• wherein an engagement of the second latching part with the first engagement portion attaches the first clipping element to the second clipping element in the first configuration, and an engagement of the second latching part with the second engagement portion attaches the first clipping element to the second clipping element in the second configuration.