Button always displays on top in FrameLayout

In the Android 5.0 (API 21) and above, you must add android:elevation into the view.

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="changeColor"
        android:text="new button"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="some text"
        android:elevation="3dp"/>

Update:

in android 21+ after introduction of elevation one can play with elevation attribute of various widgets to put them on top of one another. here is a material design guide for elevation values.

for api < 21 :

This answer

Buttons in Lollipop and higher have a default elevation to them which causes them to always draw on top. You can change this by overriding the default StateListAnimator.

Try putting this into your button XML:

android:stateListAnimator="@null"

The FrameLayout should now cover the button.