--- a/togglePanel.ur	Thu Sep 22 19:24:01 2011 +0200
+++ b/togglePanel.ur	Fri Sep 23 13:30:01 2011 +0200
@@ -1,27 +1,27 @@
 datatype panelState = Open | Closed
 
-type formatCtl = {FormatPanel : xbody -> xbody -> xbody,
-                  OpenCtl : transaction unit -> xbody,
-                  CloseCtl : transaction unit -> xbody}
+con formatCtl :: {Unit} -> Type = fn other_ctx => {FormatPanel : (xml ([Body] ++ other_ctx) [] []) -> (xml ([Body] ++ other_ctx) [] []) -> (xml ([Body] ++ other_ctx) [] []),
+                  OpenCtl : transaction unit -> xml ([Body] ++ other_ctx) [] [],
+                  CloseCtl : transaction unit -> xml ([Body] ++ other_ctx) [] []}
 
 val defaultFormat = {FormatPanel = fn ctl panel => <xml>{ctl}{panel}</xml>,
                      OpenCtl = fn behaviour => <xml><button value="Open" onclick={behaviour}/></xml>,
                      CloseCtl = fn behaviour => <xml><button value="Close" onclick={behaviour}/></xml>}
                     
-con togglePanel t = {PanelState : source panelState,
-                     FormatCtl : formatCtl,
+con togglePanel t other_ctx = {PanelState : source panelState,
+                     FormatCtl : formatCtl other_ctx,
                      Content : t}
 
 open Gui
 
-fun create [t ::: Type] (toXml : gui t xbody) (f : formatCtl) (content : t) (startOpen : bool) : transaction (togglePanel t) =
+fun create [t ::: Type] [other_ctx:::{Unit}] [other_ctx ~ body] (toXml : gui t (xml ([Body] ++ other_ctx) [] [])) (f : formatCtl other_ctx) (content : t) (startOpen : bool) : transaction (togglePanel t other_ctx) =
     state <- source (if startOpen then Open else Closed);
 
     return {PanelState = state,
             FormatCtl = f,
             Content = content}
 
-fun render [t ::: Type] (_ : gui t xbody) (panel : togglePanel t) =
+fun render [t ::: Type]  [other_ctx:::{Unit}] [other_ctx ~ body] (_ : gui t (xml ([Body] ++ other_ctx) [] [])) (panel : togglePanel t other_ctx) =
     let
         val openCtl = panel.FormatCtl.CloseCtl (set panel.PanelState Closed)
         val closeCtl = panel.FormatCtl.OpenCtl (set panel.PanelState Open)
@@ -48,4 +48,4 @@
             </xml>
     end
 
-fun gui_togglePanel [t ::: Type] (_ : gui t xbody) = mkGui render 
+fun gui_togglePanel [t ::: Type]  [other_ctx:::{Unit}] [other_ctx ~ body] (_ : gui t (xml ([Body] ++ other_ctx) [] [])) = mkGui render