438817: Task notification on luna dark theme is unreadable 

allow background colour to be set by the theme (the text colour already
is)

Change-Id: I0f0129879edb581f7ec2b431567a44f97ebb4b61
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=438817
diff --git a/org.eclipse.mylyn.commons.ui/src/org/eclipse/mylyn/commons/ui/dialogs/AbstractNotificationPopup.java b/org.eclipse.mylyn.commons.ui/src/org/eclipse/mylyn/commons/ui/dialogs/AbstractNotificationPopup.java
index 3c3427b..3891b0c 100644
--- a/org.eclipse.mylyn.commons.ui/src/org/eclipse/mylyn/commons/ui/dialogs/AbstractNotificationPopup.java
+++ b/org.eclipse.mylyn.commons.ui/src/org/eclipse/mylyn/commons/ui/dialogs/AbstractNotificationPopup.java
@@ -336,7 +336,7 @@
 		/* Outer Composite holding the controls */
 		final Composite outerCircle = new Composite(parent, SWT.NO_FOCUS);
 		outerCircle.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
-		outerCircle.setBackgroundMode(SWT.INHERIT_FORCE);
+		outerCircle.setBackgroundMode(SWT.INHERIT_NONE);
 
 		outerCircle.addControlListener(new ControlAdapter() {