The background icon is at 210,0 and yes it is being tinted during runtime.
edit: Or just check the XML, to quote from eq2ui_IconStyles.xml:
Code:
<IconStyle BackGlowRect="210,0,252,42" BackGlowResource="/images/icons/icon_transp1.dds" BackRect="84,42,126,84" BackResource="/images/icons/icon_transp1.dds" description="Same as button but no iconrect" FrameRect="126,42,168,84" FrameResource="/images/icons/icon_transp1.dds" MouseOverRect="84,84,126,126" MouseOverResource="/images/icons/icon_transp1.dds" Name="inventory" PressedRect="168,42,210,84" PressedResource="/images/icons/icon_transp1.dds" ProgressRect="84,42,126,84" ProgressResource="/images/icons/icon_transp1.dds"/>