private void UpdateInterface()
        {
            if (_documents.Count == 0)
            {
                _mainForm.NoDocumentsOpen();
            }
            else
            {
                _mainForm.DocumentsOpen();
            }

            // TODO: If running, this overrides the above to set the run button to
            // disabled. Should consolidate the two to prevent the duplication
            _mainForm.UpdateBuildControls();

            if (_focusedItem == FocusedItems.Output)
            {
                _mainForm.UndoEnabled = false;
                _mainForm.RedoEnabled = false;
                _mainForm.OutputWindowHasFocus();
                _editCommands = _outputWindow;
            }
            else if (_focusedItem == FocusedItems.Window)
            {
                _mainForm.UndoEnabled   = ActiveWindow.CanUndo;
                _mainForm.RedoEnabled   = ActiveWindow.CanRedo;
                _mainForm.ReloadEnabled = (ActiveDocument.FileType == FileType.Existing);
                _editCommands           = ActiveWindow.EditCommands;
                _mainForm.EnableEditCommands();
            }
            else
            {
                _mainForm.UndoEnabled = false;
                _mainForm.RedoEnabled = false;
                _mainForm.DisableEditCommands();
            }
        }