Provide navigation context for __imp_unavailable method.

site_ansto/instrument/util/config_edit.py

@@ -445,7 +445,7 @@ class InstConfigManager(object):
         self.opt_lb.set_focus(0)
         return
 
-    def __imp_unavailable(self, opt, imp):
+    def __imp_unavailable(self, opt, imp, action):
         """Return True if an implementation is unavailable because it is used
         by an enabled option.
         """
@@ -457,10 +457,18 @@ class InstConfigManager(object):
             return False
 
         opt_imp = self.cf_dat.opt_dict[opt]['selected_imp']
-        if opt_imp == imp:
-            return False
-        elif self.cf_dat.opt_dict[ckopt]['enabled']:
-            return True
+        if (action == 'focus'):
+            if opt_imp == imp:
+                return False
+            elif self.cf_dat.opt_dict[ckopt]['enabled']:
+                return True
+            else:
+                return False
+        elif (action == 'state_change'):
+            if self.cf_dat.opt_dict[ckopt]['enabled']:
+                return True
+            else:
+                return False
         else:
             return False
 
@@ -468,7 +476,7 @@ class InstConfigManager(object):
         """Generate the appropriate listwalker for the given option."""
         imp_items = []
         for imp in self.cf_dat.iter_implementations(opt):
-            if self.__imp_unavailable(opt, imp):
+            if self.__imp_unavailable(opt, imp, 'focus'):
                 continue
             if imp == self.cf_dat.opt_dict[opt]['selected_imp']:
                 imp_items.append((imp, True))
@@ -514,12 +522,14 @@ class InstConfigManager(object):
         opt = button.get_label().split(':')[0]
         imp = self.cf_dat.opt_dict[opt]['selected_imp']
         if new_state == True:
-            if self.__imp_unavailable(opt, imp):
+            if self.__imp_unavailable(opt, imp, 'state_change'):
                 self.cf_dat.opt_dict[opt]['selected_imp'] = 'none'
                 imp_none_button = self.imp_lw.button_dict['none']
                 imp_none_button.set_state(True)
                 opt_button = self.opt_lw.button_dict[opt]
                 opt_button.set_label('{0}:none'.format(opt))
+                self.imp_lw = self.__gen_imp_listwalker(opt)
+                self.imp_lb.use_listwalker(self.imp_lw)
             else:
                 opt_button = self.opt_lw.button_dict[opt]
                 opt_button.set_label('{0}:{1}'.format(opt, imp))
@@ -605,6 +615,7 @@ class DEBUG:
 
 DBG = DEBUG(enabled=True)
 def main(config_ini):
+    global cf_dat, cf_man, cf_viewer
     """Create configuration editor."""
 
     # Make configuration data