Android Themes: Define colors/gradients in "baseTheme.xml", use within controls, override in "subThemeX.xml"

I'm having a hard time figuring out how to implement a more complex Theme/Style situation in android.

I've studied the different Styling/Theming tutorials provided by Android, but they don't fit the bill in my case.

The (distilled) situation is the following: I'm creating an application with a custom tabwidget, and I need to be able to brand the application with different styles (themes).

The XML for the tabwidget (Based on http://joshclemm.com/blog/?p=136):

layout/tabs_bg.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tabsLayout" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:background="@drawable/tab_bg_selector"
    android:padding="10dip" android:gravity="center" android:orientation="vertical">

    <LinearLayout android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:orientation="horizontal"
        android:gravity="center">
        <ImageView          
            android:src="@drawable/star_fav_empty"
            android:layout_height="24px" 
            android:layout_width="24px"
            android:id="@+id/tabsImage"
            android:paddingRight="5dip"></ImageView>

        <TextView 
            android:id="@+id/tabsText" 
            android:layout_width开发者_Go百科="wrap_content"
            android:layout_height="wrap_content" 
            android:text="Hallowaaaaa"
            android:textSize="15dip"
            android:textColor="?android:textColorTertiary"/>
    </LinearLayout>
</LinearLayout>

drawable/tab_bg_selector.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <!--  Active tab -->
    <item android:state_selected="true" android:state_focused="false"
        android:state_pressed="false" android:drawable="@drawable/tab_bg_selected" />
    <!--  Inactive tab -->
    <item android:state_selected="false" android:state_focused="false"
        android:state_pressed="false" android:drawable="@drawable/tab_bg_unselected" />
    <!--  Pressed tab -->
    <item android:state_pressed="true" android:state_enabled="false" android:drawable="@android:color/transparent" />
    <!--  Selected tab (using d-pad) -->
    <item android:state_focused="true" android:state_selected="true"
        android:state_pressed="false" android:drawable="@android:color/transparent" />
</selector>

drawable/tab_bg_selected.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">  
    <gradient android:startColor="#A8A8A8" android:centerColor="#7F7F7F"
        android:endColor="#696969" android:angle="-90" />
</shape>

drawable/tab_bg_unselected.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient android:startColor="#5C5C5C" android:centerColor="#424242"
        android:endColor="#222222" android:angle="-90" />
</shape>

Then, I would like to define styles as follows:

values/MyBaseStyle.xml

<?xml version="1.0" encoding="utf-8"?>
<resources> 
    <style name="MyBaseStyle" parent="@android:style/Theme.Light">
    </style>    
</resources>

values/MySubStyle1.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="MySubStyle1" parent="MyBaseStyle"> 
    </style>
</resources>

values/MySubStyle2.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="MySubStyle2" parent="MyBaseStyle"> 
    </style>
</resources>

The big questions here are:

1. How can I put a gradient or a color in MyBaseStyle.xml, and use it within tab_bg_selected.xml and tab_bg_unselected.xml instead of the hardcoded gradient/color?

2. How can I override the gradient/color I defined in MyBaseStyle.xml from within MySubStyle1.xml and MySubStyle2.xml respectively, so that my custom tabwidget gets styled accordingly?

Remark: I would really like to be able to define the gradient/colors in respectively MyBaseStyle.xml, MySubStyle1.xml and MySubStyle2.xml (as opposed to defining multiple different colors within multiple different XMLfiles) to be able to keep the "styling" within one file. That way, I can outsource the branding for my application.

Can someone please help my accomplish this?

In the colors.xml in /res/values set colors for each theme

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="themeB_textColor">#e8e8e8</color>
    <color name="themeA_textColor">#fff</color>
</resources>

Then set color for views programmatically for the given theme?

//at on create grab the selected theme however it has been set - ie: through preferences
if(theme=='themeA')
{
  super.setTheme(R.style.ThemeA);
  Color textColor = getResources().getColor(R.color.themeA_textColor);
}
//later
applyTextColors(textView1,textView2...)

//make a function for applying colors
public void applyTextColors(TextView... tvs)
{
    for(TextView tv : tvs){tv.setTextColor(textColor);}
}