Persist jitsi only after meeting is joined (#20638)

* persist jitsi only after meeting is joined

Signed-off-by: Kerry Archibald <kerrya@element.io>

* lint + comment

src/vector/jitsi/index.ts

@@ -218,12 +218,6 @@ function joinConference() { // event handler bound in HTML
 
     switchVisibleContainers();
 
-    if (widgetApi) {
-        // ignored promise because we don't care if it works
-        // noinspection JSIgnoredPromiseFromCall
-        widgetApi.setAlwaysOnScreen(true);
-    }
-
     logger.warn(
         "[Jitsi Widget] The next few errors about failing to parse URL parameters are fine if " +
         "they mention 'external_api' or 'jitsi' in the stack. They're just Jitsi Meet trying to parse " +
@@ -252,6 +246,16 @@ function joinConference() { // event handler bound in HTML
     if (userId) meetApi.executeCommand("email", userId);
     if (roomName) meetApi.executeCommand("subject", roomName);
 
+    // fires once when user joins the conference
+    // (regardless of video on or off)
+    meetApi.on("videoConferenceJoined", () => {
+        if (widgetApi) {
+            // ignored promise because we don't care if it works
+            // noinspection JSIgnoredPromiseFromCall
+            widgetApi.setAlwaysOnScreen(true);
+        }
+    });
+
     meetApi.on("readyToClose", () => {
         switchVisibleContainers();