Is it a good idea for applications (application developers) to replace the check mark icon in the contextual action bar when in selection mode. Is this a good design pattern? Does it make more sense to replace that check mark with an "x"? Does it break consistency? Will it confuse users? The android selection pattern refers to the checkmark as a done action. Here's a link for some more details:
I quote from the Action Bar page:
The check sign gives you visual feedback that you have actually selected something. It is a sign that most users would have associated during their education with getting something right.
An "x" would mean that you would want to close a window or other visual element, which is not what happens here. Android users are used to pressing the Back button to return to the previous state of the application (before the selection happened).
Overall, an "x" would break consistency and would confuse users in two ways: it would give feedback that the app failed to be in a temporary selection state, and would override expectations of the "back" button's functionality.