Star4Win, like StarLing, uses Mueller's English-Russian dictionary (but we are planning to include the more comprehensive BARS soon). You can inspect the available dictionary items by pressing the F9 key (on an English word). English spellchecking is also functioning (summoned by Ctrl F9 key combination).
The dictionary is contained in 26 files whose names begin with M_ (M_A, M_B, Z_ (Zaliznyak) files are located (see above about the DICTIONARY line in config.str).
The entries in Zaliznyak's dictionary are supplied by their English equivalents (transferred there automatically from Mueller's dictionary). You may switch from one dictionary to another by moving the cursor around and pressing F9 on the word you wish to inspect (be it Russian or English). Remember that you may move the cursor in this way even while inspecting Russian paradigms: this is valuable because you may proceed in this way from perfective verbs (which rarely have English equivalents in the present dictionary) to their imperfective correlates. No matter how deep you proceed in your investigations, you can always move back one step by pressing the Escape key or go back to the original text / database by pressing Alt Escape.
If the word you need is not contained in the dictionary, you may add it after answering a number of diagnostic menu questions. The resulting information will be stored in the file user.dic.