-------------------------------------------
function: read_native_stat <0=real,1=imag,2=mask>
-------------------------------------------
keyboard equivalent: none

The "R" button on the "val3d:" entry line reads
3D volume stat files into an internal buffer (no
display change).  From there, they can be sampled
onto the surface using the adjacent "PAINT"
button.

Files can be read into one of three buffers:

  read_native_stat 0   => real component buff
  read_native_stat 1   => imaginary component buff
  read_native_stat 2   => mask buff

The input file name is the current value of
$statpatt taken from the "val3d:" entry
immediately entry to the left.

A re-read overwrites previous data in one of
the buffers.

N.B.: subsequent reads must be from BRIK or
bfloat files that have the same dimensions as the
first-read file(s).

The "R" button (wrapper tcl function for button:
read_real_or_complex_native_stats) automatically
attempts to read the partner of a file if it has
a complex-valued infix:

  _r,_i		complex-valued significance files
  _x,_y		complex-valued raw Fourier amplitude

In a tcl script, reading a complex-valued pair
of 3D stat files could be done as follows:

  setfile statpatt */scandir1/pol1_r+orig.BRIK
  read_native_stat 0
  setfile statpatt */scandir1/pol1_i+orig.BRIK
  read_native_stat 1

The setfile command is used to expand the
abbreviation to the full path.
