Implement the Edit > Paste menu entry (#683)

Closes #682

editor/src/document/document_message_handler.rs

@@ -1204,7 +1204,7 @@ impl MessageHandler<DocumentMessage, (&InputPreprocessorMessageHandler, &FontCac
 					.into(),
 				);
 
-				let mouse = mouse.map_or(ipp.mouse.position, |pos| pos.into());
+				let mouse = mouse.map_or(ipp.viewport_bounds.center(), |pos| pos.into());
 				let transform = DAffine2::from_translation(mouse - ipp.viewport_bounds.top_left).to_cols_array();
 				responses.push_back(DocumentOperation::SetLayerTransformInViewport { path, transform }.into());
 			}

editor/src/document/menu_bar_message_handler.rs

@@ -176,8 +176,13 @@ impl PropertyHolder for MenuBarMessageHandler {
 							action: MenuEntry::create_action(|_| PortfolioMessage::Copy { clipboard: Clipboard::Device }.into()),
 							..MenuEntry::default()
 						},
-						// TODO: Fix this
-						// { label: "Paste", icon: "Paste", shortcut: ["KeyControl", "KeyV"], action: async (): Promise<void> => editor.instance.paste() },
+						MenuEntry {
+							label: "Paste".into(),
+							icon: Some("Paste".into()),
+							shortcut: Some(vec![Key::KeyControl, Key::KeyV]),
+							action: MenuEntry::create_action(|_| FrontendMessage::TriggerPaste.into()),
+							..MenuEntry::default()
+						},
 					],
 				],
 			},

editor/src/frontend/frontend_message.rs

@@ -28,6 +28,7 @@ pub enum FrontendMessage {
 	TriggerFontLoad { font: Font, is_default: bool },
 	TriggerIndexedDbRemoveDocument { document_id: u64 },
 	TriggerIndexedDbWriteDocument { document: String, details: FrontendDocumentDetails, version: String },
+	TriggerPaste,
 	TriggerRasterDownload { document: String, name: String, mime: String, size: (f64, f64) },
 	TriggerTextCommit,
 	TriggerTextCopy { copy_text: String },