X11 does not apply gamma correction, brightness, etc.
(colour curves) to the cursor. Blueshift have no effect
on the cursor. It does not seem to be possible to
listen for changes in the visible cursor and edit it.
This can sometimes be circumvented by disabling
hardware cursors in xorg.conf.
  A patch for X.org is available:
    http://lists.x.org/archives/xorg-devel/2014-April/041873.html
    http://lists.x.org/archives/xorg-devel/2014-April/041985.html

The colour curves are strictly independent, it is for
example not possible to swap red and blue, or adjust
a subpixel depend on another. It is to my knowledge
not possible to do so in X11.
  Issue listen in the issue tracker:
    https://github.com/maandree/blueshift/issues/5

Blueshift requires adjustable gamma ramps. It is
very rare that video drivers do not support this.
  Issue listen in the issue tracker:
    https://github.com/maandree/blueshift/issues/5

VidMode can only modify the primary monitor.
It can potentially do adjustments on some video
drivers not supported by RandR.

X11 cannot be started when DRM is used.