Display plugins
===============

X11::Muralis::Display::Foo

Muralis should
- have a base list of capabilities (options)
such as fullscreen, tiled etc
- be able to choose which backend to use
  - be able to determine which backends are (a) installed (b) active

Plugins should have methods for
- saying what capabilities they support
- saying whether they are active (if their backend program is available)
- display the given image with the given options

Capabilities:
- centre
- colours*
- fullscreen
- rotate*
- smooth*
- tile
- zoom
- stretch**
- window+
- mirror++

* not available from many backends
** stretch is an option that needs to be added; some backends can only
do stretch or fullscreen, others can do both
+ window needs to be added, so this can be used with window managers
that make their own fake root
++ mirror isn't available from any backend, but I would like it to be
