gluPickMatrix Interface to
OpenGL function gluPickMatrix
usage: viewport = gluPickMatrix( x, y, delX, delY )
C function: void gluPickMatrix(GLdouble x, GLdouble y, GLdouble delX, GLdouble delY, GLint* viewport)
Psychtoolbox/PsychOpenGL/MOGL/wrap/_gluPickMatrix.m