Tiles, Frames, and Flickering

We have a layout defined in tiles-defs.xml like this:

And MainScreenLayout looks like this:

<%@ taglib uri="/WEB-INF/struts-tiles.tld" prefix="tiles" %>
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<html>
<head>
      <title><tiles:getAsString name="title" /></title>
</head>
<frameset rows="0, 123, *, 55" frameborder="0" border="0" framespacing="0" scrolling="no">
<frame name="hidden" src='<%=request.getContextPath()%><tiles:insert attribute="hidden"/>' noresize scrolling="no">
<frame name="toolbar" src='<%=request.getContextPath()%><tiles:insert attribute="toolbar"/>' noresize scrolling="no"> 
<frameset cols="35, *, 18" frameborder="0" border="0" framespacing="0">
            <frame name="left" src='<%=request.getContextPath()%>/ProjectSimplified/LeftSide.jsp' noresize scrolling="no">
            <frame name="content" src='<%=request.getContextPath()%><tiles:insert attribute="content"/>' noresize scrolling="auto">
            <frame name="right" src='<%=request.getContextPath()%>/ProjectSimplified/RightSide.jsp' noresize scrolling="no">
        </frameset>
        <frame name="footer" src='<%=request.getContextPath()%><tiles:insert attribute="footer"/>' noresize scrolling="no">
</frameset> 
</html>

When the first frame loads (MainScreenDynaHidden.jsp), it uses js to load the next frame (they need to be done in a certain order because of cross-frame references - I know, it's bad).

The problem we have is that when someone clicks on a link in toolbar where the target is the frame 'content', that the toolbar frame is flickering along with the footer frame.

There wasn't any flickering before we moved over to the tiles framework. I have no idea why this would happen. It is happening in many other cases where we are using frames and the tiles framework as well.

Does anyone know why this would happen or how to fix it?