How to write the description of specs2 test correctly?

I use specs2 to write Scala test, and have some questions about how to write the description.

Suppose I have a test scenario, that:

Given: a button
When: I click on it
Then: it will show a dialog with "Hello world" text

I have several ways to write the test in specs2,

1.

"a dialog with 'Hello world' text" should {
  "be shown if I click on the given button" in {
     // click on the button and checking dialog
  }
}

2.

"When I click on the given button, it" should {
  "show a dialog with 'Hello world' text" in {
     // click on the button and checking dialog
  }
}

3.

"When I click on the given button, a dialog with 'Hello world' text" should {
  "be shown" in {
     // click on the button and checking dialog
  }
}

I'm not sure which one is the best, or is there any better way?