@Override
    public void show() {
        Window dialogWindow = getWindow();
        dialogWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        startAnimation(true);
        super.show();
    }
The dialog class showing the context menu and ensures proper animation is played upon calling
{@link #show()} and {@link #dismiss()}.
customtabs/src/android/support/customtabs/browseractions/BrowserActionsFallbackMenuDialog.java