applets/notifications: Pass wheel events of TextArea to ListView

Prevent `TextArea` in SelectableLabel from accepting wheel
events when the notification item is in FullRepresentation,
and pass wheel events to `ListView` in FullRepresentation when the
cursor is over the `TextArea`.

BUG: 443840
FIXED-IN: 5.24

applets/notifications/package/contents/ui/FullRepresentation.qml

@@ -430,6 +430,7 @@ PlasmaComponents3.Page {
 
                                         inGroup: model.isInGroup
                                         inHistory: true
+                                        listViewParent: list
 
                                         applicationName: model.applicationName
                                         applicationIconSource: model.applicationIconName

applets/notifications/package/contents/ui/NotificationItem.qml

@@ -27,6 +27,7 @@ ColumnLayout {
 
     property bool inGroup: false
     property bool inHistory: false
+    property ListView listViewParent: null
 
     property alias applicationIconSource: notificationHeading.applicationIconSource
     property alias applicationName: notificationHeading.applicationName
@@ -241,6 +242,7 @@ ColumnLayout {
 
                     SelectableLabel {
                         id: bodyLabel
+                        listViewParent: notificationItem.listViewParent
                         // FIXME how to assign this via State? target: bodyLabel.Layout doesn't work and just assigning the property doesn't either
                         Layout.alignment: notificationItem.inGroup ? Qt.AlignTop : Qt.AlignVCenter
                         Layout.fillWidth: true

applets/notifications/package/contents/ui/SelectableLabel.qml

@@ -23,6 +23,7 @@ PlasmaComponents3.ScrollView {
     property int cursorShape
 
     property QtObject contextMenu: null
+    property ListView listViewParent: null
 
     signal clicked(var mouse)
     signal linkActivated(string link)
@@ -87,6 +88,18 @@ PlasmaComponents3.ScrollView {
                 });
                 contextMenu.open(mouse.x, mouse.y);
             }
+
+            // Pass wheel events to ListView to make scrolling work in FullRepresentation.
+            onWheel: {
+                if (bodyTextContainer.listViewParent
+                    && ((wheel.angleDelta.y > 0 && !bodyTextContainer.listViewParent.atYBeginning)
+                        || (wheel.angleDelta.y < 0 && !bodyTextContainer.listViewParent.atYEnd))) {
+                    bodyTextContainer.listViewParent.contentY -= wheel.angleDelta.y;
+                    wheel.accepted = true;
+                } else {
+                    wheel.accepted = false;
+                }
+            }
         }
     }