Confirm forgetting room with popup

src/qml/Popups/ForgetRoomPopup.qml

@@ -0,0 +1,21 @@
+import QtQuick 2.12
+
+BoxPopup {
+    summary.text: qsTr(
+        "You will leave the room and lose its messages. Forget %1?"
+    ).arg(roomName)
+
+    details.text: qsTr(
+        "If all members forget the room, it will be removed from the servers."
+    )
+
+    okText: qsTr("Forget")
+    box.focusButton: "ok"
+
+    onOk: py.callClientCoro(userId, "room_forget", [roomId])
+
+
+    property string userId: ""
+    property string roomId: ""
+    property string roomName: ""
+}

src/qml/SidePane/RoomDelegate.qml

@@ -124,8 +124,14 @@ HTileDelegate {
             icon.color: theme.colors.negativeBackground
             text: qsTr("Forget")
 
-            onTriggered: py.callClientCoro(
+            onTriggered: Utils.makePopup(
-                model.user_id, "room_forget", [model.data.room_id]
+                "Popups/ForgetRoomPopup.qml",
+                sidePane,
+                {
+                    userId: model.user_id,
+                    roomId: model.data.room_id,
+                    roomName: model.data.display_name,
+                }
             )
         }
     }