xrandr-mediated correction of VGA overscan on external computer monitor When I employ an external monitor (Dell E207WFP) as the display device for my laptop computer, about 10 pixels are truncated from the left edge of the screen, which I believe is a consequence of a phenomenon known as overscan (the monitor is connected to the computer by VGA). I have several accessible resolutions: 1680x1050 (60.0 Hz), 1280x1024 (75.0 Hz), 1152x864 (75.0 Hz), 1024x768 (75.1 Hz), 800x600 (75.0 Hz), 800x600 (75.0 Hz), and 720x400 (70.1 Hz). I have elected to use the highest resolution, which is the default and also the highest resolution supported by this monitor. Scaling down to a lower resolution resolves the overscan problem but is undesirable. I seek a solution that diminishes, to the lowest possible extent, the resolution of the display. I have tried to rectify the overscan problem by shifting the display by 10 pixels to the right with a concomitant rescaling of the output to ensure that a truncation of pixels from the right side of the screen does not ensue. However, I have not experienced success by tweaking the x/y rescaling value in the 2D affine transformation used by the xrandr --transform utility. Regardless of what these values are set to, the display suffers from right-sided pixel truncation if I invoke a rightward shift of the display.
I use a command of the following form:
xrandr --output VGA1 --transform 1,0,-10,0,1,0,0,0,1

The -10 refers to the translation (in pixels) of the display along the x-axis (negative values move the display rightward). The first two parameters set as 1 indicate that no re-scaling is applied to the x-axis (field 1) or y-axis (field 5). I have tried using larger (e.g., 1.05) or smaller (e.g., 0.95) scaling factors but in all cases, the display becomes overscanned on the right edge. If someone could tell me what set of values might produce the desired effect, or propose an alternative solution, I would be grateful.
Should it be of use in resolving this issue, the full output of xrandr --query is given below:
Screen 0: minimum 320 x 200, current 1670 x 1050, maximum 8192 x 8192
LVDS1 connected (normal left inverted right x axis y axis)
   1366x768       60.0 +
   1360x768       59.8     60.0  
   1024x768       60.0  
   800x60060.3     56.2  
   640x48059.9  
VGA1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 430mm x 270mm
   1680x1050      60.0*+
   1280x1024      75.0     60.0  
   1152x864       75.0  
   1024x768       75.1     60.0  
   800x60075.0     60.3  
   640x48075.0     60.0  
   720x40070.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis) 


I had the exact same issue and found that setting panning, even if the size is the same as the resolution, causes the transform option to behave more inline with my expectations. I also found it helps to explicitly state the mode at each call to xranr.
xrandr --output VGA1 --mode 1680x1050 --panning 1680x1050
xrandr --output VGA1 --mode 1680x1050 --transform 1.05,0,-10,0,1,0,0,0,1