When re-using an individual circuit as part of a nested app, you need to edit that circuit's _lay/ files (templates) so that they don't have <html>...</html>, <body>...</body>, [include($valErrormsg)], [include($feedbackmsg)] and [include($debug)].  The $valErrormsg and $feedbackmsg display the circuit's errorMessage and feedbackMessage files and so you'll have 2 displayed once nested (see fbx_Globals.inc).


-----------------------------------------------------------------
NOTE:
the css/  (and all files inside it) WILL be used ONLY IF you use the $currentpath var like this:

<link rel="stylesheet" type="text/css" href="[$currentpath][$css]style.css">

so you have to keep in mind how it will affect the look of that circuit/override the Parent apps' css



the scripts/  (and all files inside it) WILL be used ONLY IF you use the $currentpath var like this:

<link rel="stylesheet" type="text/css" href="[$currentpath][$js]scripts.js">

so you have to keep in mind how it will affect/override the Parent apps' javascripts

-----------------------------------------------------------------
Files UNUSED in an individual circuit when it becomes part of a nested app:

_common/  (and all files inside it)
logs/  (and all files inside it)

fbx_Circuits.inc
fbx_CustomTags.inc
fbx_Globals.inc
fbx_LassoFusebox3.inc
fbx_Library.inc
fbx_Sessions.inc
index.html
index.lasso

(You'll need to copy paths/code from the nested  fbx_Circuits.inc, fbx_CustomTags.inc and  fbx_Sessions.inc to the matching files in the Parent app.)

-----------------------------------------------------------------
the 2012 Lasso Developer's Conference demo files have an example of nested apps in action