One of my co-workers just complained to me that a source file I edited contained quotation marks that are not visible when the file is viewed with VI. How can I configure UltraEdit to avoid this?
You can't configure UltraEdit to correct your mistakes. If you insert instead of the standard double quote character " (dec. 34, hex. 22) or the standard single quote character ' (dec. 39, hex. 27) from the ASCII table, language (= codepage) specific variants like
bottom single quote ‚ (dec. 130, hex. 82)
bottom double quote „ (dec. 132, hex. 84)
right single quote ‘ (dec. 145, hex. 91)
left single quote ’ (dec. 146, hex. 92)
right double quote “ (dec. 147, hex. 93)
left double quote ” (dec. 148, hex. 94)
then it is not the fault of UltraEdit when your co-worker complains about not readable quotes when using VI and a different codepage than you. Just press the keys on your keyboard for the ASCII double and single quotes. If that is too difficult for you, you can create 6 macros saved in 1 macro file which is specified to be automatically loaded on startup of UltraEdit. All 6 macros have a hotkey, the keys you press to insert the 6 language specific quotes. The macro commands are very simple. 3 macros have only """ as macro command and the other 3 only "'". With those auto-loaded macros you would always insert ASCII double and single quotes independent which quote key you hit on your keyboard.