Since I used Grocery_Crud i always automatically try to start the search action with Enter, but nothing happened so i have to click with the mouse on the Search-Button.
With a tiny modification in the list_template.php it could be changed.
File: assets/grocery_crud/themes/flexigrid/views/list_template.php
Search for the "<div class="sDiv quickSearchBox" id='quickSearchBox'....."
Here you find nearby "<input type="button" value="<?php echo $this->l('list_search');?>" class="crud_search" id='crud_search'>"
change the <input type="button" to <input type="submit"
Now it ist easy to search in the lists by Enter :).
Greetings
Robert.