Force screen resolution in Lubuntu

Connecting an ASRock Beebox N3000 with Lubuntu 16.04 to a Sony Bravia with a HDMI cable this is the output of xrandr: Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767 DP1 disconnected (normal left inverted right x axis y axis) DP2 disconnected (normal left inverted right x axis y axis) DP3 disconnected (normal left inverted right x axis y axis) HDMI1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 735mm x 420mm 1920x1080i 50.00*+ 60.00 59.94 1280x720 60.00 50.00 59.94 720x576 50.00 720x576i 50.00 720x480 60.00 59.94 720x480i 60.00 59.94 640x480 60.00 59.94 HDMI2 disconnected (normal left inverted right x axis y axis) HDMI3 disconnected (normal left inverted right x axis y axis) VIRTUAL1 disconnected (normal left inverted right x axis y axis) 1920x1080i is supposed to work well, but it results in a too wide desktop, such that it does not stay within the screen limits. Another laptop connected by VGA performs reasonably well with 1360x768, but this resolution is not supported here. xrandr --addmode HDMI1 1360x768 results in xrandr: cannot find mode "1360x768" don't know if this modeline can be added. I have also tried to change the TV configuration, but there's little to do under a HDMI connection.