Disable notification type/method combinations that are not available

framework/core/ember/app/components/ui/yesno-input.js

@@ -9,6 +9,7 @@ export default Ember.Component.extend({
   classNames: ['yesno-control'],
 
   toggleState: true,
+  disabled: false,
 
   didInsertElement: function() {
     var component = this;

framework/core/ember/app/components/user/notification-grid.js

@@ -43,7 +43,8 @@ export default Ember.Component.extend({
           type: type,
           method: method,
           enabled: !!user.get(preferenceKey),
-          loading: false
+          loading: false,
+          disabled: typeof user.get(preferenceKey) == 'undefined'
         });
         cell.set('save', function(value, component) {
           cell.set('loading', true);

framework/core/ember/app/styles/flarum/settings.less

@@ -31,7 +31,7 @@
     border-bottom: 1px solid @fl-body-bg;
     color: @fl-body-control-color;
   }
-  & td, & th, & .yesno-cell .yesno {
+  & td, & th, & .yesno {
     padding: 10px 15px;
   }
   & thead {
@@ -47,14 +47,21 @@
     }
   }
   & .yesno-cell {
+    padding: 0;
+  }
+  & .yesno-control {
+    display: block;
+  }
+  & .yesno {
     text-align: center;
     cursor: pointer;
-    padding: 0;
 
+    &:not(.disabled) {
       &:hover, &.highlighted {
         background: darken(@fl-body-control-bg, 4%);
       }
     }
+  }
   & .toggle-group {
     cursor: pointer;
   }

framework/core/ember/app/templates/components/user/notification-grid.hbs

@@ -12,7 +12,7 @@
       <tr>
         <td class="toggle-group" {{action "toggleType" row.type}}>{{row.label}}</td>
         {{#each row.cells as |cell|}}
-          <td class="yesno-cell">{{ui/yesno-input toggleState=cell.enabled changed=cell.save loading=cell.loading}}</td>
+          <td class="yesno-cell">{{ui/yesno-input toggleState=cell.enabled changed=cell.save loading=cell.loading disabled=cell.disabled}}</td>
         {{/each}}
       </tr>
     {{/each}}