I am using a field for filelist where I want to bring only png files
<field name="menu_icon"
type="filelist"
default=""
hide_default="true"
required="true"
label="JSM_CUSTOM_MENYV_SELECT_ICON"
description="JSM_CUSTOM_MENYV_SELECT_ICON_DESC"
directory="media/com_jeemasmsmobile/menuicons"
filter="*.png" exclude="" stripext="" />
What filter should I apply???