Question

<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:drawable="@drawable/key" />
<item
android:state_pressed="true"
android:drawable="@drawable/key_pressed" />
<item
android:state_checkable="true"
android:drawable="@drawable/key_function" />
<item
android:state_checkable="true"
android:state_pressed="true"
android:drawable="@drawable/key_pressed" />
<item
android:state_checkable="true"
android:state_checked="true"
android:drawable="@drawable/key_function" />
<item
android:state_checkable="true"
android:state_checked="true"
android:state_pressed="true"
android:drawable="@drawable/key_pressed" />
</selector>

test result:

normal key ->@drawable/key

normal key pressed ->@drawable/key_pressed

Sticky key->@drawable/key_function

Sticky key pressed ->@drawable/key_function <—here is the problem

Answer 1

The selection is not based on the “best match,” but simply the first
item that meets the minimum criteria of the state.

http://developer.android.com/guide/topics/resources/drawable-resource.html#StateList

So it’s the wrong drawable because one of those states is matching the current state

<item
android:state_checkable="true"
android:drawable="@drawable/key_function" />  
<item
android:state_checkable="true"
android:state_checked="true"
android:drawable="@drawable/key_function" />

Try to put

<item
android:state_checkable="true"
android:state_checked="true"
android:state_pressed="true"
android:drawable="@drawable/key_pressed" />

at the top or add criterias to the previous cases.