Block the undo shortcut while dragging with a tool (#1675)

Add NOOP message and bind it to CTRL + Z + LMB

editor/src/messages/portfolio/document/document_message.rs

@@ -15,6 +15,7 @@ use serde::{Deserialize, Serialize};
 #[impl_message(Message, PortfolioMessage, Document)]
 #[derive(PartialEq, Clone, Debug, Serialize, Deserialize)]
 pub enum DocumentMessage {
+	Noop,
 	// Sub-messages
 	#[child]
 	Navigation(NavigationMessage),

editor/src/messages/portfolio/document/document_message_handler.rs

@@ -892,6 +892,7 @@ impl MessageHandler<DocumentMessage, DocumentInputs<'_>> for DocumentMessageHand
 					responses.add(NavigationMessage::FitViewportToBounds { bounds, prevent_zoom_past_100: true });
 				}
 			}
+			Noop => (),
 		}
 	}
 
@@ -1522,6 +1523,7 @@ impl DocumentMessageHandler {
 
 	pub fn actions_with_graph_open(&self) -> ActionList {
 		let mut common = actions!(DocumentMessageDiscriminant;
+			Noop,
 			Undo,
 			Redo,
 			SelectAllLayers,