what we need:
1. APK Manager (apkmultitool.com) or apktool
2. Notepad ++ to edit file
3. two png file 240x320px.

I suggest to use different pic. one is dark, while the one is light. rename the dark one as 'bekgron_hitam' and the light one as 'bekgron_putih'.

preparation step.
1. Copy file "framework-res.apk" from /system/framework/ to folder 'place-apk-here-for-modding' in your APK Manager.
2. copy "framework-res.apk" to C:/Users/<User name>/apktool/framework/ then rename it as 1.apk

1. run Script.bat in APK Manager. type '22' Enter (Set Current Project), choose framework-res.apk.
2. Decompile "framework-res.apk" by type '9' Enter. You'll get a 'framework-res.apk' in "projects" folder. minimize the cmd.
3. go to /projects/framework-res.apk/res/values/
4. open styles.xml with Notepad ++, in line 38, 39, 40 you'll found:
Code:

<style name="Theme">
<item name="colorForeground">@color/bright_foreground_dark</item>
<item name="colorBackground">@color/background_dark</item>

replace with
Code:

<style name="Theme">
<item name="colorForeground">@color/bright_foreground_dark</item>
<item name="colorBackground">@color/transparent</item>

====
got to line 75
Code:

<item name="windowBackground">@drawable/screen_background_dark</item>

replace with:
Code:

<item name="windowBackground">@drawable/bekgron_hitam</item>
====

go to line 188, 189, 190
Code:

<style name="Theme.Black" parent="@style/Theme">
<item name="colorBackground">@color/black</item>
<item name="windowBackground">@color/black</item>

replace with:
Code:

<style name="Theme.Black" parent="@style/Theme">
<item name="colorBackground">@color/black</item>
<item name="windowBackground">@color/transparent</item>

====
go to line 232, 233, 234
Code:

<style name="Theme.Light" parent="@style/Theme">
<item name="colorForeground">@color/bright_foreground_light</item>
<item name="colorBackground">@color/background_light</item>

replace with:
Code:

<style name="Theme.Light" parent="@style/Theme">
<item name="colorForeground">@color/bright_foreground_light</item>
<item name="colorBackground">@color/transparent</item>


this part is to make static background.
go to line 247
Code:

<item name="windowBackground">@drawable/screen_background_light</item>

replace with:
Code:

<item name="windowBackground">@drawable/bekgron_putih</item>

Save styles.xml.

5. copy the picture to /projects/framework-res.apk/res/drawable-ldpi/
6. Compile framework-res.apk by type '11' enter in cmd.
7. press y until you got this message.
====
In the apk manager folder u'll find
a keep folder. Within it, delete
everything you have modified and leave
files that you haven't. If you have modified
any xml, then delete resources.arsc from that
folder as well. Once done then press enter
on this script.
====
8. a new folder will appear, its /keep/. delete file resources.arsc.
9. press any key to continue in cmd. you'll got 'unsignedframework-res.apk' in 'place-apk-here-for-modding' folder. rename it then push to your system.

this one is my modified one style.xml. please recheck the script.
http://www.mediafire.com/download.php?kshqg6ux48dqywd

all credits for heriawan.fx
m ony translate it