Opening a File with Another Application

You can easily open a file by dragging and dropping it onto an application icon in the Finder or the Dock. This is handy if you want to open a file with an application other than the one that would open it by default; for example, if you want to open an image file using QuickTime Player instead of Preview.

Getting Started with Mac OS X version 10.2 > Working with Applications > Opening a File with Another Application