A computing system for operating a plurality of computing devices (12, 14, 16), the computing system comprising one of the computing devices and an image composing unit for generating a common video signal for a display device, wherein said one computing device is adapted for: partitioning a display area of the display device into a plurality of display area sections (24, 26, 28), wherein at least one of the display area sections (24, 26) is related to at least one other computing device; receiving an input signal from at least one input device (32, 34, 36), wherein the input signal is relatable to a position within the display area; and providing the at least one other computing device (14, 16) with the input signal depending on the position being in one of the display area sections (24, 26, 28) related to said other computing device (14, 16), wherein the image compositing unit is adapted for combining image components (46, 48, 50) for displaying on the display device, wherein the image components (46, 48, 50) are related to the one computing device and at least one other computing device (14, 16); wherein the computer system is characterised in that the image composing unit is further adapted for: receiving a set of source signals, wherein each source signal is related to a computing device (12, 14, 16); determining a key information from a first source signal of the one computing device, the determined key information corresponding to the plurality of display area sections (24, 26, 28); and switching between the source signals of the different image sources (52, 54, 56) in dependence of the determined key information to create the common video signal. partitioning a display area of the display device into a plurality of display area sections (24, 26, 28), wherein at least one of the display area sections (24, 26) is related to at least one other computing device; receiving an input signal from at least one input device (32, 34, 36), wherein the input signal is relatable to a position within the display area; and providing the at least one other computing device (14, 16) with the input signal depending on the position being in one of the display area sections (24, 26, 28) related to said other computing device (14, 16), wherein the image compositing unit is adapted for combining image components (46, 48, 50) for displaying on the display device, wherein the image components (46, 48, 50) are related to the one computing device and at least one other computing device (14, 16); wherein the computer system is characterised in that the image composing unit is further adapted for: receiving a set of source signals, wherein each source signal is related to a computing device (12, 14, 16); determining a key information from a first source signal of the one computing device, the determined key information corresponding to the plurality of display area sections (24, 26, 28); and switching between the source signals of the different image sources (52, 54, 56) in dependence of the determined key information to create the common video signal. receiving a set of source signals, wherein each source signal is related to a computing device (12, 14, 16); determining a key information from a first source signal of the one computing device, the determined key information corresponding to the plurality of display area sections (24, 26, 28); and switching between the source signals of the different image sources (52, 54, 56) in dependence of the determined key information to create the common video signal.