Per IRC discussion, I've re-run these with additional logging of the value of `ThreadListUI.fullHeight`

1. the FxOS phone screen off, no apps open, rec'd message, tap icon: **path entered**, value: 0
2. the FxOS phone screen off, but Messages app open and "minimized", rec'd message, tap notification: **path not entered**, value: 410
3. the FxOS phone screen on, but Messages app closed, rec'd message, tap notification: **path not entered**, value: 410
4. the FxOS phone screen on, but Messages app open and "minimized", rec'd message, tap icon: **path not entered**, value: 410

This is the logging code:

```js
  onVisibilityChange: function mm_onVisibilityChange(e) {
    LinkActionHandler.reset();
    console.log( "onVisibilityChange", ThreadListUI.fullHeight );
    // If we receive a message with screen off, the height is
    // set to 0 and future checks will fail. So we update if needed
    if (!ThreadListUI.fullHeight || ThreadListUI.fullHeight === 0) {
      console.log( "Setting ThreadListUI.fullHeight" );
      ThreadListUI.fullHeight = ThreadListUI.container.offsetHeight;
    }
```