Notify parents/children when an app closes

Send an appClosed message with the instance ID of the app that was
closed. This will be picked up by Puter.js's AppConnection and reported
as a 'close' event.

To make this work, a `data-parent_instance_id` attribute is set on child
app windows. This is very similar to the `data-parent_uuid` attribute,
which tracks parent windows instead of parent app instances. (Dialogs
have a parent window, but are not apps, so don't have a parent app
instance.) The difference is subtle, and we may want to combine these in
the future, but currently closing an app will close any child windows,
which is not behaviour we want for child apps.

src/UI/UIWindow.js

@@ -185,6 +185,7 @@ async function UIWindow(options) {
                 data-uid ="${options.uid}"
                 data-element_uuid="${options.element_uuid}"
                 data-parent_uuid="${options.parent_uuid}"
+                ${options.parent_instance_id ? `data-parent_instance_id="${options.parent_instance_id}"` : ''}
                 data-id ="${win_id}"
                 data-iframe_msg_uid ="${options.iframe_msg_uid}"
                 data-is_dir ="${options.is_dir}"
@@ -2745,8 +2746,9 @@ $.fn.close = async function(options) {
     options = options || {};
     $(this).each(async function() {
         const el_iframe = $(this).find('.window-app-iframe');
+        const app_uses_sdk = el_iframe.length > 0 && el_iframe.attr('data-appUsesSDK') === 'true';
         // tell child app that this window is about to close, get its response
-        if(el_iframe.length > 0 && el_iframe.attr('data-appUsesSDK') === 'true'){
+        if(app_uses_sdk){
             if(!options.bypass_iframe_messaging){
                 const resp = await sendWindowWillCloseMsg(el_iframe.get(0));
                 if(!resp.msg){
@@ -2819,6 +2821,30 @@ $.fn.close = async function(options) {
             }
             // close child windows
             $(`.window[data-parent_uuid="${window_uuid}"]`).close();
+
+            // notify other apps that we're closing
+            if (app_uses_sdk) {
+                // notify parent app, if we have one, that we're closing
+                const parent_id = this.dataset['parent_instance_id'];
+                const parent = $(`.window[data-element_uuid="${parent_id}"] .window-app-iframe`).get(0);
+                if (parent) {
+                    parent.contentWindow.postMessage({
+                        msg: 'appClosed',
+                        appInstanceID: window_uuid,
+                    }, '*');
+                }
+
+                // notify child apps, if we have them, that we're closing
+                const children = $(`.window[data-parent_instance_id="${window_uuid}"] .window-app-iframe`);
+                children.each((_, child) => {
+                    child.contentWindow.postMessage({
+                        msg: 'appClosed',
+                        appInstanceID: window_uuid,
+                    }, '*');
+                });
+                // TODO: Once other AppConnections exist, those will need notifying too.
+            }
+
             // remove backdrop
             $(this).closest('.window-backdrop').remove();
             // remove DOM element

src/helpers.js

@@ -1853,6 +1853,10 @@ window.launch_app = async (options)=>{
     let icon, title, file_signature;
     const window_options = options.window_options ?? {};
 
+    if (options.parent_instance_id) {
+        window_options.parent_instance_id = options.parent_instance_id;
+    }
+
     // try to get 3rd-party app info
     let app_info = options.app_obj ?? await get_apps(options.name);