[android] Dialog with transparent background in Android

Make sure R.layout.themechanger has no background color because by default the dialog has a default background color.

You also need to add dialog.getWindow().setBackgroundDrawable(newColorDrawable(Color.TRANSPARENT));

And finally

<style name="TransparentDialog">
    <item name="android:windowIsFloating">true</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowTitleStyle">@null</item>
</style>