Up until now, if you double-clicked on a file from the Finder, it would open up automatically in the application that created it.

Several calls from AppleWorks 6.0 users after they updated to OSX 10.6 Snow Leopard alerted me to a problem: double-clicking on a AppleWorks file brought up a message that the file could not be opened. But if they first opened up AppleWorks, the file would open.

Something else was happening for people who created files that were saved with extensions that identified the file type instead of the application that created it. For example, hand-coded HTML files with the extension .html might open up in Safari instead of BBEdit or DreamWeaver!

The reason for this type of error stems from a technical change in how 10.6 Snow Leopard manages files. Up through OSX 10.5 Leopard, the Finder would look at file metadata called a Creator Code to identify the source application. Now, your computer simply looks at the file extension, the part of the filename after the period (for example, resume.doc is a Word document, and resume.cwk was made in AppleWorks).

To solve any similar errors, here’s what you can do:

View the file in your Finder.
Click on it one time to select it.
Press ?-I or File?Get Info.
Look for a section called Open With. Click on the flippy triangle to its left if you can’t see the details in the section.
Click the blue arrows to drop down the file type.
If your desired application is on the list, choose it. Then, click the “Change All…” button.
If your desired application is NOT on the list, click “Other…”, then navigate to the application you need the file to open in. Put a checkmark in front of “Always Open With.”
From now on, when you double-click on a file with that file type, it should open just fine.

This trick is also good for always opening Word documents with Pages. Or, if you’re upgrading from AppleWorks to iWorks, you can use this to open your AppleWorks word processing files to Pages and your spreadsheets in Numbers!