I solved the problem - turned out to be very easy:

var filteredData ;
                    if ($scope.filterCriteria)
                        filteredData = $filter('filter')($scope.unassignedItems, $scope.filterCriteria);
                    else
                        filteredData = $scope.unassignedItems;

                    var unassignedItems = filteredData.slice(0);
                    var smItems = filteredData.slice(0);

>Hi everybody,
>
>I have the following directive (html):
>
>

>@using Siriusware.Resources;
><div class="form-horizontal">
>    <div class="col-xs-5 pull-left">
>        <div class="form-group">
>            <label class="control-label">{{unassignedItemsTitle}}</label>
>            <div>
>                <select class="select-list" multiple
>                        ng-model="unassigned"
>                        name="unAssignedList"
>                        data-no-dirty-check
>                        ng-options="unassignedItem.descrip for unassignedItem in unassignedItems | orderBy:'descrip' | filter: filterCriteria"></select>
>            </div>
>        </div>
>    </div>
>
>    <div class="col-xs-2 pull-left" style="text-align: center; padding: 25px;">
>        <button ng-click="moveRight(unassigned)" class="btn btn-block"><i class="fa fa-angle-right icon-1x"></i></button>
>        <button ng-click="moveRightAll()" class="btn btn-block"><i class="fa fa-angle-double-right icon-1x"></i></button>
>        <button ng-click="moveLeft(assigned)" class="btn btn-block"><i class="fa fa-angle-left icon-1x"></i></button>
>        <button ng-click="moveLeftAll()" class="btn btn-block"><i class="fa fa-angle-double-left icon-1x"></i></button>
>    </div>
>
>    <div class="col-xs-5 pull-left">
>        <div class="form-group">
>            <div>
>                <label class="control-label">{{assignedItemsTitle}}   </label>
>                <span class="pull-right" ng-show="sortable && assigned != null && assignedItems.length > 1 ">
>                    <a class="badge" ng-click="moveUp(assigned)" data-toggle="tooltip" title="@Labels.moveUp"
>                       sm:blankanchor><i class="fa fa-angle-up icon-1x"></i></a>
>                    <a class="badge" ng-click="moveDown(assigned)" data-toggle="tooltip" title="@Labels.moveDown"
>                       sm:blankanchor><i class="fa fa-angle-down icon-1x"></i></a>
>                </span>
>            </div>
>            <div>
>                <select class="select-list"
>                        ng-change="onChanged(assigned)" 
>                        multiple
>                        data-no-dirty-check
>                        ng-model="assigned"
>                        name="assignedList"
>                        ng-options="assignedItem.descrip for assignedItem in assignedItems| orderBy: 'SortOrder' | filter: filterCriteria">
>                </select>
>            </div>
>        </div>
>    </div>
></div>

>
>So, as you can see, I can specify the filter-criteria and the items will be properly filtered. Ok, so far so good.
>
>Now, I have the following code for the MoveRightAll (and similar for MoveLeftAll):
>
>

>$scope.moveRightAll = function() {
>                    var unassignedItems = $scope.unassignedItems.slice(0);
>                    var smItems = $scope.unassignedItems.slice(0);
>
>                    angular.forEach(smItems, function (value, key) {
>                        $scope.assignedItems.push(value);
>                        removeItem(unassignedItems, value);
>                    });
>                    $scope.unassignedItems = unassignedItems;
>                    if (!$scope.keepPristine)
>                        $scope.form.$setDirty();
>                    
>                    $scope.assigned = null;
>                };

>
>So, the problem here that this code doesn't respect the filter. Say, I filtered items by department and category and then clicked on move all button, all 642 items are getting moved instead of just a few from that category.
>
>So, I just want to get the filtered list at the top if I have something in the $scope.filterCritera.
>
>Thanks in advance.