Add config.pushAtKeyPath/removeAtKeyPath

src/app/config.coffee

@@ -144,6 +144,30 @@ class Config
       @update()
     value
 
+  # Push the value to the array at the key path.
+  #
+  # keyPath - The {String} key path.
+  # value - The value to push to the array.
+  #
+  # Returns the new array length of the setting.
+  pushAtKeyPath: (keyPath, value) ->
+    arrayValue = @get(keyPath) ? []
+    result = arrayValue.push(value)
+    @set(keyPath, arrayValue)
+    result
+
+  # Remove the value from the array at the key path.
+  #
+  # keyPath - The {String} key path.
+  # value - The value to remove from the array.
+  #
+  # Returns the new array value of the setting.
+  removeAtKeyPath: (keyPath, value) ->
+    arrayValue = @get(keyPath) ? []
+    result = _.remove(arrayValue, value)
+    @set(keyPath, arrayValue)
+    result
+
   # Establishes an event listener for a given key.
   #
   # `callback` is fired immediately and whenever the value of the key is changed

src/app/package-config-panel.coffee

@@ -29,12 +29,10 @@ class PackageConfigPanel extends ConfigPanel
     @on 'change', '#packages input[type=checkbox]', (e) ->
       checkbox = $(e.target)
       name = checkbox.closest('tr').attr('name')
-      disabledPackages = config.get('core.disabledPackages')
       if checkbox.attr('checked')
-        _.remove(disabledPackages, name)
+        config.removeAtKeyPath('core.disabledPackages', name)
       else
-        disabledPackages.push(name)
-      config.set('core.disabledPackages', disabledPackages)
+        config.pushAtKeyPath('core.disabledPackages', name)
 
     @observeConfig 'core.disabledPackages', (disabledPackages) =>
       @packageTableBody.find("input[type='checkbox']").attr('checked', true)

src/stdlib/underscore-extensions.coffee

@@ -4,6 +4,7 @@ _.mixin
   remove: (array, element) ->
     index = array.indexOf(element)
     array.splice(index, 1) if index >= 0
+    array
 
   spliceWithArray: (originalArray, start, length, insertedArray, chunkSize=100000) ->
     if insertedArray.length < chunkSize