You can't get an undocked recording window to go behind the browser window.

Manifests in IE 11, Chrome 40, FF 32.0

Note this is while working with resolution set to 1280 x 720 for recording.

Environment:
Windows Server 2012R2 as a VMWare guest.
IE 11.0.9600
Chrome 40.0.2214
Firefox 32.0

Repro steps:

0) Start IE recorder
1) Navigate to a page
2) Undock recording window
3) Click on browser window

Expected: Recording pane goes to background; browser window is in foreground
Actual: Recording pane blocks browser window; doesn't go to background.