RootsMagic has a Character Map (Ctrl-T) where you can select special characters, such as diacritic accents to use in any data entry field. If you are in an event note you can also choose Tools>Character Map to enter characters.
This will allow you to select your keyboard in a particular language. You probably already selected English as the primary input language when you first setup your computer.
Now when you click on the task bar language icon, a select language box comes up and allows you to select one of the languages you added. Your keyboard is now configured for that language and layout. When you exit, your computer automatically returns your keyboard to the primary language (English).
To assist you in learning what keys represent which characters, you can set up the on-screen keyboard.
When you are entering data in Roots Magic 4 and need to enter Swedish (or other) and /or letters with the diacritics or accents, etc, simply click on the Language icon, select the language, then click on the task bar for the on-screen keyboard.
The on-screen keyboard is not very large so it does not cover most of the input data you are working on. You can use your keyboard while noting the on-screen character lay out in that language or you can use the mouse on the 0n-screen keyboard. No hunting through all foreign characters. Everything you need in one language is right there. In Swedish, most of the diacritic characters or letters are on the far right where the brackets and colons are. Most everything else is the same qwerty layout you use in the English keyboard.
To learn more about Microsoft's Language Bar and On-Screen keyboard go to:
HOW TO: Use the Language Bar in Windows XP
Using On-Screen Keyboard