Fix for Bug 378921 - Incorrect drag and drop behavior.

bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java

diff --git a/bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java b/bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java
index 2b60e63..b89d64d 100644
--- a/bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java
+++ b/bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java
@@ -571,7 +571,7 @@
 				psc.getChildren().add(0, toInsert);
 			else
 				psc.getChildren().add(toInsert);
-		} else if (relToParent instanceof MPartSashContainer
+		} else if (relToParent instanceof MPartSashContainer && !(relToParent instanceof MArea)
 				&& directionsMatch((MPartSashContainer) relToParent, horizontal)) {
 			MPartSashContainer psc = (MPartSashContainer) relToParent;
 			int relToIndex = psc.getChildren().indexOf(relTo);