A fastening system (100, 100A, 100B) for a window shade, comprising: a first clipping base and a second clipping base adapted to attach to each other for holding one or more panels of a window shade; wherein the fastening system (100, 100A, 100B) has a first configuration where the first and second clipping bases (102, 104) are attached to each other, and wherein the fastening system (100, 100A, 100B) has a second configuration; characterised in that the fastening system (100, 100A, 100B) further comprises: a first and a second clipping plate (106, 108) respectively positionable between the first clipping base and the second clipping base; wherein the fastening system (100, 100A, 100B) has the first configuration where the first and second clipping bases (102, 104) are attached to each other with each of the first and second clipping plates (106, 108) respectively disposed between and in contact with the first and second clipping bases (102, 104), and the second configuration where the first and second clipping bases (102, 104) are attached to each other without the first and second clipping plates (106, 108) between the first and second clipping bases (102, 104), the fastening system (100, 100A) in the first configuration being adapted to hold a first panel of a window shade between the first clipping base and the first and second clipping plates (106, 108) and to hold a second panel of a window shade between the second clipping base and the first and second clipping plates (106, 108), and the fastening system (100, 100B) in the second configuration being adapted to hold a single panel of a window shade between the first clipping base and the second clipping base, the fastening system (100, 100A, 100B) being attachable in the first and second configurations via a plurality of latches (134, 140, 150). a first clipping base and a second clipping base adapted to attach to each other for holding one or more panels of a window shade; wherein the fastening system (100, 100A, 100B) has a first configuration where the first and second clipping bases (102, 104) are attached to each other, and wherein the fastening system (100, 100A, 100B) has a second configuration; characterised in that the fastening system (100, 100A, 100B) further comprises: a first and a second clipping plate (106, 108) respectively positionable between the first clipping base and the second clipping base; wherein the fastening system (100, 100A, 100B) has the first configuration where the first and second clipping bases (102, 104) are attached to each other with each of the first and second clipping plates (106, 108) respectively disposed between and in contact with the first and second clipping bases (102, 104), and the second configuration where the first and second clipping bases (102, 104) are attached to each other without the first and second clipping plates (106, 108) between the first and second clipping bases (102, 104), the fastening system (100, 100A) in the first configuration being adapted to hold a first panel of a window shade between the first clipping base and the first and second clipping plates (106, 108) and to hold a second panel of a window shade between the second clipping base and the first and second clipping plates (106, 108), and the fastening system (100, 100B) in the second configuration being adapted to hold a single panel of a window shade between the first clipping base and the second clipping base, the fastening system (100, 100A, 100B) being attachable in the first and second configurations via a plurality of latches (134, 140, 150).