Nice, looking good. Thank you. Making good progress. I can now drag-drop a color from one panel to another. In Morphic the layout would then be responsible for determining at which position in the submorph collection this would be added. In morphic that is done with LayoutPolicy>>indexForInserting: aMorph at: aPoint in: someMorph "Return the insertion index based on the layout strategy defined for some morph. Used for drop insertion." ^1 "front-most" which is only overridden in TableLayout. Is that a separate responsibility in Bloc or is that part of the responsibility of a LayoutStrategy (or even an EventListener)? Stephan