Bug 533374: [Dark] Compare for new files shows white background

Change-Id: If0199505fefde500a9454e62f8468535c04857af
Signed-off-by: Matthias Becker <ma.becker@sap.com>
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/MergeSourceViewer.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/MergeSourceViewer.java
index 2887708..ff6070a 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/MergeSourceViewer.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/MergeSourceViewer.java
@@ -563,7 +563,9 @@
 			if (c != null) {
 				c.setEnabled(enabled);
 				Display d= c.getDisplay();
-				c.setBackground(enabled ? d.getSystemColor(SWT.COLOR_LIST_BACKGROUND) : null);
+				if (enabled) {
+					c.setBackground(d.getSystemColor(SWT.COLOR_LIST_BACKGROUND));
+				}
 			}
 		}
 	}