In order not to continuously alternate windows (with the Alt+Tab shortcut or with mouse clicking) you can arrange these three windows horizontally on your screen.
Below you can find a screenshot of a proposed arrangement so that you have full view of Word, Translator's Workbench and Concordance. A 1024x768 screen resolution was used. Higher resolutions can give you more space and lower resolutions can hardly support this layout.
You have to manually resize each window and move it to the appropriate location.