Adding text preview in Windows Explorer based on file extension

This is so simple and has likely been around for some time but somehow I have not come across this technique until a colleague showed me today. I am not going to give a step by step guide simply because if you don’t understand how to do what I describe then I recommend that you don’t do it. Or at the very least, don’t do it until you have more experience.

In the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Classes there is a key for each known extension (e.g. .wsdl). Under this key, you need to add a string value (REG_SZ) called PerceivedType and set its value to “text” (without the quotation marks).

You do not have to reboot the machine nor even restart Windows Explorer as every time focus is given to a different file then the registry is checked.