How to Open Icons in OS X Mountain Lion
You can open any icon in the Mountain Lion Finder — whether it’s a file or a folder — in at least six ways. (Okay, there are at least seven ways, but one of them belongs to aliases.) Anyway, here are the ways:
Click the icon once to select it and choose File→Open.
Click the icon twice in rapid succession.
If the icon doesn’t open, you double-clicked too slowly. You can test (and adjust) your mouse’s sensitivity to double-click speed in the Mouse (or Trackpad) System Preferences pane, which you can access by launching the System Preferences application (from the Applications folder, the Dock, or the Apple menu) and then clicking the Mouse (or Trackpad) icon.
Select the icon and then press either Command+O or cmd+down arrow.
Right-click or Control-click it and then choose Open from the contextual menu.
If the icon is a document, drag it onto the application icon (or the Dock icon of an application) that can open that type of document.
If the icon is a document, right-click or Control-click it and choose an application from the Open With submenu of the contextual menu.
You can also open any document icon from within an application, of course. Here’s how that works:
Just launch your favorite program, and choose File→Open (or press Command+O, which works in most Mac programs).
An Open dialog appears.
When you use a program’s Open dialog, only files that the program knows how to open appear enabled (in black rather than light gray) in the file list. In effect, the program filters out the files it can’t open, so you barely see them in the Open dialog.
This method of selectively displaying certain items in Open dialogs is a feature of most applications. Therefore, when you’re using TextEdit, its Open dialog dims all your spreadsheet files (because TextEdit can open only text, Rich Text Format, Microsoft Word, and some picture files). Pretty neat, eh?
In the dialog, simply navigate to the file you want to open (using the same techniques you use in a Save sheet).
Select your file, and click the Open button.
For what it’s worth, some applications allow you to select multiple files in their Open dialogs by holding down either Shift (for contiguous selections) or Command (for noncontiguous selections). If you need to open several files, it’s worth a try; the worst thing that could happen is that it won’t work and you’ll have to open the items one at a time.
Some programs, including Microsoft Word and Adobe Photoshop, have a Show or Format menu in their Open dialogs. This menu lets you specify the type(s) of files you want to see in the Open dialog. You can often open a file that appears dimmed by choosing All Documents from the Show or Format menu (in those applications with Open dialogs that offer such a menu).