Check spelling in more than one language
The key to this is Check spelling in current input language. First make sure that you have all the languages you want to use installed as Windows Input languages. Then use the Language Bar to switch languages.
A few things to note:
- The default setting when adding a new input language in Control Panel is to use the keyboard layout appropriate to that language. Unless you’re familiar with the other keyboard layout (French swaps Q and A, for example), select the keyboard you’re used to at this stage.
- The language bar can be collapsed to a small two-letter language abbreviation on the taskbar. Just click the tiny minimize button.
- With more than one input language installed, the default keyboard shortcut for changing language is Alt + Left Shift. This will cycle between installed languages, so if there are only two, it acts as a toggle.
Then, with Check my spelling as I type selected and mixed language in a message compose window, you should see wiggly red lines swapping places as you press Alt-Left Shift.