mozilla-b2g/gaia — pull request #3330 by RudyLu (2012-08-10 08:27:39+00:00)
Title: Fix the issue to make keyboard overlay functional

Keyboard overlay is used to enable switching focus between inputs.

**Root cause**:
The #windows div was given a z-index 1, which would cause it stay above keyboard iFrame (set as 0), so we could not click the keyboard anymore.

**Solution**:
Remove the z-index setting so that the order would be,
1. #windows > iframe.appWindow
2. #keyboard-frame
3. #windows

Here is a detailed explanation on how this works,
https://developer.mozilla.org/en-US/docs/CSS/Understanding_z-index/Stacking_context_example_1