start initial work on detaching chat to floating window

Modules/Notifications/Sidebar/Chat/ChatContent.qml

@@ -11,7 +11,7 @@ import qs.Services
 Item {
 	id: root
 
-	required property ChatSession chatData
+	property ChatSession chatData
 	property bool following: true
 	readonly property int messageCount: chatData.messages.length
 
@@ -257,7 +257,7 @@ Item {
 
 		anchors.fill: parent
 		spacing: Tokens.spacing.small
-		visible: root.messageCount === 0 && !Chat.busy
+		visible: (root.messageCount === 0 && !Chat.busy) || !root.chatData
 
 		Item {
 			Layout.fillHeight: true
@@ -273,7 +273,7 @@ Item {
 		CustomText {
 			Layout.alignment: Qt.AlignHCenter
 			color: Colors.tPalette.m3onSurfaceVariant
-			text: qsTr("No messages yet")
+			text: !root.chatData ? qsTr("Open a previous chat or start a new one") : qsTr("No messages yet")
 		}
 
 		Item {