Is there a way to show only specific file extensions?

Solution 1:

Open the Registry Editor, navigate to HKCR (although HKCU\Software\Classes would be a better location, but most are lazy). For every file type, create a zero-length string value named AlwaysShowExt.

For example, if you have .txt:

1. Navigate to the subkey for the extension – HKCR\.txt – and note the data stored in the "(Default)" value – it usually says txtfile.

2. Navigate to the file type subkey HKCR\txtfile, right-click the value list, choose New → String value, and name the new value AlwaysShowExt.

Not all extensions have separate subkeys for file types – sometimes all information is kept directly under HKCR\.myext. In such cases, AlwaysShowExt goes directly to the extension subkey as well.

It is very likely that there are dedicated programs for editing file types, possibly with support for AlwaysShowExt and other flags. I don't know any to recommend, though.