Magento, on administration side, has the concept of “grid”, a table with ability to filter, order, page a collection of data. For example the product list is a grid.
A grid is usually initialized on block implementation that “prepares columns” and when I needed to change the columns of a grid I overloaded the block implementation with a class of mine extending the original one.
The latest modification I made on Magento was on product list tab present on category detail. I found incredibly stupid in Magento the absence of a category filter on product management panel and an edit action on product list on category detail.
Since the simpler thing was to add an action to that table I overrided the