Add support for reordering document tabs (#3999)

* Add support for reordering document tabs

* Fix tab bar scrolling

* Close tab without activating it on pointerdown

editor/src/messages/portfolio/portfolio_message.rs

@@ -126,6 +126,10 @@ pub enum PortfolioMessage {
 		layers: Vec<LayerNodeIdentifier>,
 	},
 	PrevDocument,
+	ReorderDocument {
+		document_id: DocumentId,
+		new_index: usize,
+	},
 	RequestWelcomeScreenButtonsLayout,
 	RequestStatusBarInfoLayout,
 	SetActivePanel {

editor/src/messages/portfolio/portfolio_message_handler.rs

@@ -1053,6 +1053,24 @@ impl MessageHandler<PortfolioMessage, PortfolioMessageContext<'_>> for Portfolio
 					responses.add(PortfolioMessage::SelectDocument { document_id: prev_id });
 				}
 			}
+			PortfolioMessage::ReorderDocument { document_id, new_index } => {
+				let new_index = new_index.min(self.document_ids.len().saturating_sub(1));
+				let Some(current_index) = self.document_ids.iter().position(|&id| id == document_id) else {
+					return;
+				};
+
+				if new_index != current_index {
+					self.document_ids.remove(current_index);
+					self.document_ids.insert(new_index, document_id);
+
+					responses.add(PortfolioMessage::UpdateOpenDocumentsList);
+
+					// Re-send the active document so the frontend recalculates the active tab index after reordering
+					if let Some(active_document_id) = self.active_document_id {
+						responses.add(FrontendMessage::UpdateActiveDocument { document_id: active_document_id });
+					}
+				}
+			}
 			PortfolioMessage::RequestWelcomeScreenButtonsLayout => {
 				let donate = "https://graphite.art/donate/";