I'm slow sometimes..
If you want to change that background, once you have the apk decompiled, go into the res/values folder and open up colors.xml and edit these...
<color name="header_background_light1">#ff7a7a7a</color>
<color name="header_background_medium1">#ff000000</color>
<color name="header_background_medium2">#ff0a0a0a</color>
<color name="header_background_medium3">#ff000000</color>
<color name="header_background_dark1">#ff808080</color>
<color name="header_background_dark2">#ff000000</color>
<color name="header_background_highlight1">#ff878787</color>
<color name="header_background_highlightTransparent1">#00a3a3a3</color>
<color name="header_background_highlight2">#ffa3a3a3</color>
<color name="header_background_highdark1">#ff969696</color>
<color name="header_background_highdarkTransparent1">#00a0a0a0</color>
<color name="header_background_highdark2">#ff0a0a0a</color>
That above is from "darkside" So, mostly black. The highlight's and highdarks are for the little slivers and such. The others control various sections of that "green" background you are wanting to change.
Lastly, in that code up there, there are NO SPACES.. for some reason, even though they are not there when I type this, they appear when I post it.
My suggestion to you, do what I did. Grab a piece of paper, write down the code for each one and make each one really different from each other. Like one code make purple, make one red, one black, one pink, etc... Then recompile and install and note which header changes what. Then, go back in and change them so they look like you want them to with the color(s) you want. No real need to mess with the two transparent ones.
That's good information you posted xkape. I'm jumping on the creative wagon with you guys.