Does not get focus in fluxbox. Unable to capture keyboard.

[slackhead]

I'm using fluxbox WM and dzen 0.8.5.

I have a shell script that detects new windows opening on other workspaces than the current. What I want to do is optionally press enter and go to that workspace.

This is a snippet of the code I've been testing:

DIFF="2"
DZEN="dzen2 -x 0 -y $(($Y-25)) -w 70 -h 25 -l 1 -bg black -fg gray -e 'key_Return=exit:9'"
(echo "[ $DIFF ]"; sleep 15) | $DZEN

When the window pops up it doesn't have focus and pressing enter just goes to the terminal.
If I click the mouse on it and then press enter it doesn't change.