a video signal combining apparatus comprises a video signal processing unit which is adapted to combine an output video image stream from two input image streams from first and second sources by dividing an image area of an image of said output video image stream into two regions and applying to said first region image information from said first source and applying to said second region image information from said second source , and a display unit for displaying at least one of said input and output video image streams , characterized in that the display unit is adapted to display a border between said first and second regions superimposed upon an image from one of said sources .