pantalla xrandr

Select the window whose client you wish to kill with button 1....
xkill:  killing creator of resource 0x3800002
vianstak@CDE:~$ xrandr
Screen 0: minimum 8 x 8, current 1280 x 720, maximum 16384 x 16384
DVI-I-0 disconnected (normal left inverted right x axis y axis)
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 1280x720+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1920x1080      30.0 +   30.0
   1440x480       30.0
   1280x720       60.0*    59.9
   720x480        59.9     30.0
   640x480        59.9     59.9