SetErrorBarSize — Set the size of the error bar tee.
$plot->SetErrorBarSize($ebs
)
SetErrorBarSize
sets the length of the 'tee' drawn at
the top and bottom of error bars, if the error bar shape is set to 'tee'
with SetErrorBarShape (or defaulted to 'tee').
The default size is 5 pixels.
This is only used with error plots (data types data-data-error and data-data-yx-error), and with error bar shape 'tee'.
All lines in a plot use the same error bar size.