19/80: installer: Handle the 'back' action in the filesystems task.

[John Darrington]

jmd pushed a commit to branch wip-installer
in repository guix.

commit 758578723de3b1e441387a2ef78fb80c3ad0bd96
Author: John Darrington <address@hidden>
Date:   Thu Dec 22 19:17:42 2016 +0100

    installer: Handle the 'back' action in the filesystems task.
    
    * gnu/system/installer/filesystems.scm: Add key handler for Back function.
---
 gnu/system/installer/filesystems.scm |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gnu/system/installer/filesystems.scm 
b/gnu/system/installer/filesystems.scm
index 79fb2a0..ed35393 100644
--- a/gnu/system/installer/filesystems.scm
+++ b/gnu/system/installer/filesystems.scm
@@ -120,6 +120,11 @@
        ((page-refresh next) next)
        ))
 
+     ((buttons-key-matches-symbol? nav ch 'back)
+      (delwin (outer (page-wwin page)))
+      (delwin (inner (page-wwin page)))
+      (set! page-stack (cdr page-stack)))
+
      
      ((buttons-key-matches-symbol? nav ch 'continue)
       (cond