Let's take a look at a specific example to understand how to modify Koha code.
Let's say we want to add the Google Indic Transliteration tool to the masthead on the OPAC. This tool transliterates text in the source language to a destination language selected from a drop-down list. The transliterated expression can be then be used as a search expression.
This feature requires the following changes:
Modify the CSS file to position the transliteration control
Modify the search box on the masthead to accept input in the source language
Add the language selector drop-down list to the right of the search box
Include a Google-provided JavaScript file; the transliteration is performed by this file
Add a new system preference to control the availability of the tool