code: function getUserInstalledTheme() {
          var result = new $.Deferred();
  
          var installedTheme = themesPref.get("theme"),
              bracketsTheme;
  
          if (installedTheme === "light-theme" || installedTheme === "dark-theme") {
              return result.resolve(installedTheme);
          }
  
          if (!ExtensionManager.hasDownloadedRegistry) {
              ExtensionManager.downloadRegistry().done(function () {
                  bracketsTheme = ExtensionManager.extensions[installedTheme];
                  if (bracketsTheme && bracketsTheme.installInfo && bracketsTheme.installInfo.locationType === ExtensionManager.LOCATION_USER && bracketsTheme.registryInfo) {
                      result.resolve(installedTheme);
                  } else {
                      result.reject();
                  }
              })
                  .fail(function () {
                      result.reject();
                  });
          } else {
              bracketsTheme = ExtensionManager.extensions[installedTheme];
              if (bracketsTheme && bracketsTheme.installInfo && bracketsTheme.installInfo.locationType === ExtensionManager.LOCATION_USER && bracketsTheme.registryInfo) {
                  result.resolve(installedTheme);
              } else {
                  result.reject();
              }
          }
  
          return result.promise();
      }
docs: Utility function to get the user installed theme which are present in the registry