fixed type in RootLayer, which I found because I triggered a bug

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12049 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/servers/app/RootLayer.cpp

@@ -1075,7 +1075,7 @@ void RootLayer::MouseEventHandler(int32 code, BPortLink& msg)
 // TODO: lock here!
 			Layer		*target = LayerAt(evt.where);
 			if (target == NULL)
-				debugger("RooLayer::MouseEventHandler: 'target' can't be null.\n");
+				debugger("RootLayer::MouseEventHandler: 'target' can't be null.\n");
 			WinBorder	*winBorderUnder = NULL;
 
 			// fEventMaskLayer is always != this
@@ -1812,4 +1812,4 @@ void RootLayer::empty_visible_regions(Layer *layer)
 		empty_visible_regions(child);
 		child = layer->VirtualUpperSibling();
 	}
-}
+}