Index: openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl,v
diff -u -N -r1.147 -r1.148
--- openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl	1 Nov 2018 14:16:18 -0000	1.147
+++ openacs-4/packages/acs-tcl/tcl/request-processor-procs.tcl	19 Nov 2018 18:19:12 -0000	1.148
@@ -468,14 +468,17 @@
 
 ad_proc -private rp_resources_filter { why } {
 
-    This filter runs on all URLs of the form /resources/*.  The acs-resources package
-    mounts itself at /resources but we short circuit references here in order to
-    maximize throughput for resource files.  We just ns_returnfile the file, no
-    permissions are checked, the ad_conn structure is not initialized, etc.
+    This filter runs on all URLs of the form /resources/*.  We just
+    ns_returnfile the file, no permissions are checked, the ad_conn
+    structure is not initialized, etc in order to maximize throughput
+    for resource files.
 
     There are three mapping possibilities:
 
-    /resources/package-key/* maps to root/packages/package-key/www/resources/*
+    /resources/package-key/* maps to
+    root/packages/package-key/www/resources/*. This mapping is theme
+    aware and will be therefore overridden by
+    root/packages/<theme_package>/resources/templates/packages/package-key/www/resources.
 
     If that fails, we map to root/packages/acs-subsite/www/resources/*
     If that fails, we map to root/www/resources/*
@@ -492,7 +495,18 @@
     }
 
     ad_conn -set untrusted_user_id 0
-    set path "[acs_package_root_dir [lindex [ns_conn urlv] 1]]/www/resources/[join [lrange [ns_conn urlv] 2 end] /]"
+
+    set urlv [ns_conn urlv]
+    set package_key [lindex $urlv 1]
+    set resource [join [lrange $urlv 2 end] /]
+
+    set path "packages/$package_key/www/resources/$resource"
+    set themed_path [template::resource_path -type templates -style $path]
+    if { [file isfile $themed_path] } {
+        return [rp_serve_resource_file $themed_path]
+    }
+
+    set path "[acs_package_root_dir $package_key]/www/resources/$resource"
     if { [file isfile $path] } {
         return [rp_serve_resource_file $path]
     }
Index: openacs-4/packages/acs-templating/tcl/util-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/util-procs.tcl,v
diff -u -N -r1.41 -r1.42
--- openacs-4/packages/acs-templating/tcl/util-procs.tcl	3 Nov 2018 19:52:29 -0000	1.41
+++ openacs-4/packages/acs-templating/tcl/util-procs.tcl	19 Nov 2018 18:19:12 -0000	1.42
@@ -705,7 +705,8 @@
 
         if {$theme_dir ne ""} {
             set path $theme_dir/$type/$style
-            if {![file exists $::acs::rootdir/$path.adp]} {
+            set lookup_path [expr {[file extension $path] eq "" ? "${path}.adp" : $path}]
+            if {![file exists $::acs::rootdir/$lookup_path]} {
                 unset path
             }
         }
Index: openacs-4/packages/xowiki/tcl/chat-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/chat-procs.tcl,v
diff -u -N -r1.40 -r1.41
--- openacs-4/packages/xowiki/tcl/chat-procs.tcl	19 Nov 2018 16:35:12 -0000	1.40
+++ openacs-4/packages/xowiki/tcl/chat-procs.tcl	19 Nov 2018 18:19:12 -0000	1.41
@@ -387,10 +387,11 @@
     set context id=$chat_id&s=$session_id
     set base_url ${path}ajax/chat?${context}
 
-    # This will point to chat/resources/chat.css for a chat instance
-    # and to <xowiki_mountpoint>/resources.chat.css for a plain xowiki
-    # chat
-    template::head::add_css -href ${path}resources/chat.css
+    # Get the css from resources folder in the right package depending
+    # on chat implementation (chat or xowiki package). Request
+    # processor will serve the proper themed css when available.
+    set package_key [apm_package_key_from_id $package_id]
+    template::head::add_css -href /resources/${package_key}/chat.css
 
     if {$mode eq ""} {
       #