Activity를 Dialog로 띄우기

AndroidManifest.xml 설정

<activity android:name=".DialogTest"
             android:theme="@android:style/Theme.Dialog">
</activity>

타이틀 영역 없애기

requestWindowFeature(Window.FEATURE_NO_TITLE);

Dialog 배경을 투명하게 처리

protected void onApplyThemeResource(Resources.Theme theme, int resid, boolean first){
    super.onApplyThemeResource(theme,resid,first);
    theme.applyStyle(style.Theme_Panel,true);
}