You can change the types of files recognized by the DevStudio editor by adding the file type to the following registry key: HKEY_CURRENT_USERSoftwareMicrosoftDevStudio5.0IstudioProjectEditors

For example, to allow JavaScript source files (.js) to be edited in the DevStudio editor, add the subkey “.js” to the key specified above. Then create a string value of “:Source Editor” under the new key and change the “(Default)” entry to “:Source Editor”. Now when you double-click a JavaScript file in DevStudio, it will be opened in the DevStudio editor.