Add message box with instructions before updating

js/api.js

@@ -191,7 +191,7 @@ const Blockbench = {
 		}
 	},
 	showMessageBox(options = 0, cb) {
-		new MessageBox(options, cb).show();
+		return new MessageBox(options, cb).show();
 	},
 	async textPrompt(title, value, callback, placeholder = null) {
 		let answer = await new Promise((resolve) => {

js/desktop.js

@@ -648,10 +648,20 @@ window.onbeforeunload = function (event) {
 	}
 }
 
-function closeBlockbenchWindow() {
+async function closeBlockbenchWindow() {
 	for (let project of ModelProject.all.slice()) {
 		project.closeOnQuit();
 	}
+	if (Blockbench.hasFlag('update_downloaded')) {
+		await new Promise(resolve => {
+			Blockbench.showMessageBox({
+				title: 'message.installing_update.title',
+				message: tl('message.installing_update.message', '60'),
+				icon: 'update',
+				width: 534
+			}, resolve);
+		})
+	}
 	window.onbeforeunload = null;
 	Blockbench.addFlag('allow_closing');
 	Blockbench.dispatchEvent('before_closing')
@@ -694,6 +704,7 @@ ipcRenderer.on('update-available', (event, arg) => {
 			console.error(err);
 		})
 		ipcRenderer.on('update-downloaded', (event) => {
+			Blockbench.addFlag('update_downloaded');
 			action.setName(tl('message.update_after_restart'));
 			MenuBar.menus.help.removeAction(action);
 			icon_node.textContent = 'done';

lang/en.json

@@ -290,6 +290,8 @@
 	"message.update_notification.title": "Could not Install Update",
 	"message.update_notification.message": "A new Blockbench version is available. Please enable Automatic Updates in the settings in order to update!",
 	"message.update_after_restart": "The update will be installed after the next restart",
+	"message.installing_update.title": "Update Available",
+	"message.installing_update.message": "A new version is ready to be installed. After closing the app, please allow for around %0 seconds before opening Blockbench again or turning off the computer, for the update to be installed.",
 	"message.import_particle_texture.import": "Import Particle Texture",
 	"message.import_particle_texture.message": "Would you like to import a texture file to be used for your particle?",