>>>> "When the user clicks the login button, the main screen appears"
>>
>>Passive voice, but: "When the login button is clicked, the main screen appears"
>
>I can't tell you how many editors I fought with about that one. Apparently, lots of teachers teach that passive voice is never okay. I would argue that it's perfect for cases where the actor is unknown or irrelevant. Usually, I won. <g>
>

Write in the active voice, not the passive voice -- Strunk and White. I do not view it as a bible but it does have a lot of good advice for anyone who wants to write well.

http://www.amazon.com/The-Elements-Style-William-Strunk/dp/1481913417/ref=sr_1_2?ie=UTF8&qid=1370014592&sr=8-2&keywords=the+elements+of+style

$6.26, amazing.