Fix bugs of pending keys of animated menu. - When more than one pending key, the animation would be stoped. - Now, we have a cyclic queue to keep at most 15 pending keys to make sure pending keys being dispatched without stop current animation program.

<project>
	<scene src="/tmp/scene.mbsvg"/>
	<scene src="/tmp/second.mbsvg"/>
	<source src="/tmp/main.c"/>
	<source src="/tmp/second.c"/>
</project>