since this thread has been moved to the advanced section,,i might as well ask some suggestion to the script,no?

1. the zenity progress bar is supposed to show real progress not just pulsating back and forth..but i can't get it to work.my guess is i messed something in sed regular expression but i dont know which part.
2. i'm thinking of using gtkdialog so that every command box can be put into a window,and got the basic idea of how to use it for this script,but the axel - sed - zenity part of the script just not fit in gtkdialog xml format..and i'd like to ask how the "case statement" of my script can be put into gtkdialog radiolist action.
here's the draft,,yes i know this script is plain wrong..just bear with me please

#!/bin/bash
export main='
<window><frame Axel DM>
<hbox>
<text><label>Add URL</label></text>
<entry><variable>url</variable></entry>
</hbox>
<hbox homogeneous="true" spacing="20">
<button>
<label>Download now!</label>
<action>axel -n 10 '$url' --output '$places' &</action>
</button>
</hbox>
</frame>
<frame>
<hbox>
<list>
<variable>LIST</variable>
<item>First item</item>
<item>Second item</item>
<item>Third item</item>
<action>echo Chosen item is $LIST</action>
</list>
</hbox>
</frame>
</window>
'
gtkdialog --program=main