SetXTickLength
SetXTickLength — Set outer length of X tick marks
Synopsis
$plot->SetXTickLength($xln)
    
Description
SetXTickLength sets the length of the X tick marks
pointing outwards from the plot. For example, for tick marks on an X axis
at the bottom of the plot, this is the length from the X axis down.
    
Parameters
- $xln
- 
Desired X tick length in pixels.