In several places in Piwik's Web interface, pressing the backspace key will delete two characters instead of one, if by doing so it can delete a space at the end of the input.

Steps to reproduce:

• Go to "manage" a Goal, either by creating a new one or clicking the edit icon for an existing goal in the "manage" menu.
• Click at the end of the Description field
• enter some non-space characters, one space, and then one more non-space character. For example, "abc d"
• press backspace once. It will delete two characters (the space, and the final non-space character)
• it ought to delete only one character, leaving the space intact.

I'm running Piwik 3.1.1, server is Linux, Apache, PHP 5.6.31; client is Linux, Pale Moon. It happens to me in every text field in the interface that has fancy fade-in and similar features, throughout the settings and configuration screens, but not in the "search" box and a few other places.