Basically, in order to read or write Yiddish text, in the standard format, on a computer, you must check for only 2-3 settings in each program (i.e., each application):

1. Encoding - Unicode UTF-8 (Don't worry, it's just a setting, to make it uniform, so that one person's Yiddish text will show up consistently on another person's computer.)
2. Paragraph Direction - Right-to-Left (RTL) [Note that "paragraph direction" is specific and is not the same as "text direction."]
3. Keyboard Language - Yiddish (This last is only needed to type Yiddish. If you plan to read only, with no typing, you don't technically need this either, but you'll miss all the fun.)

So, when evaluating any new program or makherayke to see if it can handle Yiddish text, and how to do it, simply search around all the preference and option menus for all of the above. Actually, the last one, the Yiddish Keyboard, is something you will normally set at the operating system level. See the instructions linked from the Home Page. So, all you have to look for are the first two. If you find them, make note of how to change the settings and/or decide if you want to change defaults or make toolbar shortcuts within the application, if available.