Android: “BadTokenException: Unable to add window; is your activity running?” at showing dialog in PreferenceActivity

I had a very similar issue (which landed me here) and found a very simple fix for it. While my code is different, it should be easy to adapt. Here is my fix:

public void showBox() {
    mActive = true;
    if (! ((Activity) mContext).isFinishing()) {
        mDialogBox.show();
    }
} 

So, in the sample code in the question, the fix would have been (at a guess):

@Override
public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
    if (key.equals("checkTest")) {
        if (! this.isFinishing()) {
            showDialog(1);
        }
    }
    if (key.equals("cancel")) {
        dismissDialog(1);
    }
}// onSPC