diff --git a/Ide/projwin.icl b/Ide/projwin.icl
index 338dac9e32c5542da0974ab6cf507bd2eb17dccb..d46101cb2da32c1b93ad97964fb487626ff657a5 100644
--- a/Ide/projwin.icl
+++ b/Ide/projwin.icl
@@ -538,16 +538,63 @@ where
 				= makenice u s r
 		where
 			f mod	= if shift
-						(OpenModule (MakeDefPathname mod) emptySelection)
-						(OpenModule (MakeImpPathname mod) emptySelection)
+						(open_def mod)	//(OpenModule (MakeDefPathname mod) emptySelection)
+						(open_imp mod)	//(OpenModule (MakeImpPathname mod) emptySelection)
 			f` mod	= if shift
-						(OpenModule (MakeImpPathname mod) emptySelection)
-						(OpenModule (MakeDefPathname mod) emptySelection)
+						(open_imp mod)	//(OpenModule (MakeImpPathname mod) emptySelection)
+						(open_def mod)	//(OpenModule (MakeDefPathname mod) emptySelection)
 			isUnfoldedDir d Nil = False
 			isUnfoldedDir d ((u,d`):!ds)
 				| d == d` = u
 				= isUnfoldedDir d ds
+
+open_def mod ps
+	# defpath		= MakeDefPathname mod
+//	# (exists,ps)	= accFiles (FExists defpath) ps
+	# (exists,ps)	= exists_module defpath ps
+	| exists
+		= OpenModule defpath emptySelection ps
+	# lhspath		= RemoveSuffix mod  +++ ".lhs"
+//	# (exists,ps)	= accFiles (FExists lhspath) ps
+	# (exists,ps)	= exists_module lhspath ps
+	| exists
+		= OpenModule lhspath emptySelection ps
+	# hspath		= RemoveSuffix mod  +++ ".hs"
+//	# (exists,ps)	= accFiles (FExists hspath) ps
+	# (exists,ps)	= exists_module hspath ps
+	| exists
+		= OpenModule hspath emptySelection ps
+	= OpenModule defpath emptySelection ps
 	
+open_imp mod ps
+	# defpath		= MakeImpPathname mod
+//	# (exists,ps)	= accFiles (FExists defpath) ps
+	# (exists,ps)	= exists_module defpath ps
+	| exists
+		= OpenModule defpath emptySelection ps
+	# lhspath		= RemoveSuffix mod  +++ ".lhs"
+//	# (exists,ps)	= accFiles (FExists lhspath) ps
+	# (exists,ps)	= exists_module lhspath ps
+	| exists
+		= OpenModule lhspath emptySelection ps
+	# hspath		= RemoveSuffix mod  +++ ".hs"
+//	# (exists,ps)	= accFiles (FExists hspath) ps
+	# (exists,ps)	= exists_module hspath ps
+	| exists
+		= OpenModule hspath emptySelection ps
+	= OpenModule defpath emptySelection ps
+
+exists_module pathname ps
+	# (syspaths,ps)			= getCurrentPaths ps
+	# (prj,ps)				= getProject ps
+	# prjpaths				= PR_GetPaths prj
+	# srcpaths				= AppendLists prjpaths syspaths
+	# srcpaths				= case IsABCPathname pathname of
+		True	-> Map MakeSystemPathname srcpaths
+		_		-> srcpaths
+	# ((ok,fullpath),ps)	= accFiles (SearchDisk False pathname srcpaths) ps
+	= (ok,ps)
+
 // pm_set: set main module
 pm_set :: !*(PSt *General) -> *PSt *General
 pm_set ps