I'm not 100% sure if this is a bug, but:
Code
<style name="popup_lightbox_style" width="100%" height="100%" onloaded="layer[popup_container].open()" keep="true" scalechildren="false" align="center" bgcapture="true" handcursor="true" alpha="0" bgcolor="0x000000" bgalpha="0.5" zorder="100" autoalpha="true" open="tween(layer[popup_container].alpha, 1);" close="tween(layer[popup_container].alpha, 0);" onclick="close()" enabled="true" />
<layer name="popup_container" type="container" style="popup_lightbox_style" >
<layer name="link_63" type="container" bgcolor="0xbb1c21" bgalpha="1" align="center" width="85" height="85" x="85" y="85" scalechildren="false" maskchildren="true" keep="true" />
</layer>
The parent layer has "popup_container" has a style "popup_lightbox_style", within this style there's a property keep="true". The layer "link_63" is not shown.
If I remove keep="true" from popup_lightbox_style, and put it in popup_container, then link_63 is shown.
I'm not sure if keep="true" is copied over to the layer "popup_container" or if it applies to the style node. But it shouldnt affect "link_63" I'd guess.