A data processing system comprising: a computer; a display device; and an indication assembly for the data processing system, the indication assembly comprising: a first control assembly (230, 530, 1010) mounted on a surface of the computer, comprising a first sensor (236, 536, 1022) and a first indicator (235, 535), the first sensor and the first indicator being coupled to a first sensing circuit (233,533), wherein the first sensing circuit is arranged to send an electrical signal to the first indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said first sensor; and a second control assembly (201, 501, 1011) mounted on a surface of the display device coupled to said computer, comprising a second sensor (206, 506, 1031) and a second indicator (205, 505), the second sensor and second indicator being coupled to a second sensing circuit (203, 503), wherein the second sensing circuit is arranged to send an electrical signal to the second indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said second sensor; wherein said first control assembly and said second control assembly are configured to share a signal source to synchronise the behaviours of said first indicator and said second indicator when said user-touch occurs to either one of said first control assembly and said second control assembly. a computer; a display device; and an indication assembly for the data processing system, the indication assembly comprising: a first control assembly (230, 530, 1010) mounted on a surface of the computer, comprising a first sensor (236, 536, 1022) and a first indicator (235, 535), the first sensor and the first indicator being coupled to a first sensing circuit (233,533), wherein the first sensing circuit is arranged to send an electrical signal to the first indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said first sensor; and a second control assembly (201, 501, 1011) mounted on a surface of the display device coupled to said computer, comprising a second sensor (206, 506, 1031) and a second indicator (205, 505), the second sensor and second indicator being coupled to a second sensing circuit (203, 503), wherein the second sensing circuit is arranged to send an electrical signal to the second indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said second sensor; wherein said first control assembly and said second control assembly are configured to share a signal source to synchronise the behaviours of said first indicator and said second indicator when said user-touch occurs to either one of said first control assembly and said second control assembly. a first control assembly (230, 530, 1010) mounted on a surface of the computer, comprising a first sensor (236, 536, 1022) and a first indicator (235, 535), the first sensor and the first indicator being coupled to a first sensing circuit (233,533), wherein the first sensing circuit is arranged to send an electrical signal to the first indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said first sensor; and a second control assembly (201, 501, 1011) mounted on a surface of the display device coupled to said computer, comprising a second sensor (206, 506, 1031) and a second indicator (205, 505), the second sensor and second indicator being coupled to a second sensing circuit (203, 503), wherein the second sensing circuit is arranged to send an electrical signal to the second indicator for controlling its presentation and a power control signal to the computer when a user-touch occurs to said second sensor; wherein said first control assembly and said second control assembly are configured to share a signal source to synchronise the behaviours of said first indicator and said second indicator when said user-touch occurs to either one of said first control assembly and said second control assembly.