[quadrapassel] Disable preview-button in difficult block mode

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 0e9f6f3a77f4ef26fdd0823b22d766a99fd10ada
Author: Mario Wenzel <maweki gmail com>
Date:   Sun Apr 21 19:15:51 2013 +0200

    Disable preview-button in difficult block mode
    
    Since preview doesnt work for difficult block mode, the gui should
    make availability of this button dependent on other settings.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=669624

 src/quadrapassel.vala |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/quadrapassel.vala b/src/quadrapassel.vala
index 696883f..72c5bda 100644
--- a/src/quadrapassel.vala
+++ b/src/quadrapassel.vala
@@ -355,6 +355,7 @@ public class Quadrapassel : Gtk.Application
 
         do_preview_toggle = new Gtk.CheckButton.with_mnemonic (_("_Preview next block"));
         do_preview_toggle.set_active (settings.get_boolean ("do-preview"));
+        do_preview_toggle.set_sensitive(!settings.get_boolean ("pick-difficult-blocks"));
         do_preview_toggle.toggled.connect (do_preview_toggle_toggled_cb);
         grid.attach (do_preview_toggle, 0, 4, 2, 1);
 
@@ -477,6 +478,7 @@ public class Quadrapassel : Gtk.Application
     private void difficult_blocks_toggled_cb ()
     {
         settings.set_boolean ("pick-difficult-blocks", difficult_blocks_toggle.get_active ());
+        do_preview_toggle.set_sensitive(!settings.get_boolean ("pick-difficult-blocks"));
     }
 
     private void set_rotate_counter_clock_wise ()