refactor: replace DragHandler with MouseArea for app dragging

1. Replaced DragHandler with MouseArea for better drag control and
simpler implementation
2. Changed drag state detection from dragHandler.active to drag.active
3. Simplified drag initialization by directly setting Drag.active from
mouseArea
4. Removed complex state management and replaced with direct property
binding
5. Combined left/right click handling in single MouseArea for cleaner
code
6. Improved drag image handling by showing/hiding background during
drag operation
7. Fixed potential crash issues by eliminating the need for external
dndItem

refactor: 使用 MouseArea 替换 DragHandler 处理应用拖拽

1. 使用 MouseArea 替换 DragHandler 以获得更好的拖拽控制和更简单的实现
2. 将拖拽状态检测从 dragHandler.active 改为 drag.active
3. 通过直接从 mouseArea 设置 Drag.active 简化了拖拽初始化
4. 移除了复杂的状态管理，改用直接属性绑定
5. 在单个 MouseArea 中合并左右键点击处理，代码更清晰
6. 改进了拖拽图像处理，在拖拽操作期间显示/隐藏背景
7. 通过消除对外部 dndItem 的需求修复了潜在的崩溃问题

Author: wjyrich

qml/windowed/AppListView.qml

@@ -165,7 +165,7 @@ FocusScope {
                     leftMargin: 10
                     rightMargin: 10
                 }
-                visible: !dragHandler.active
+                visible: !Drag.active
                 text: model.display
                 checkable: false
                 icon.name: (iconName && iconName !== "") ? iconName : "application-x-desktop"
@@ -206,69 +206,45 @@ FocusScope {
                 ToolTip.visible: hovered && contentItem.implicitWidth > contentItem.width
 
                 Drag.dragType: Drag.Automatic
+                Drag.active: mouseArea.drag.active
                 Drag.mimeData: Helper.generateDragMimeData(model.desktopId, true)
                 Drag.hotSpot.y: height / 2
                 Drag.hotSpot.x: width / 2
 
-                states: State {
-                    name: "dragged";
-                    when: dragHandler.active
-                    // FIXME: When dragging finished, the position of the item is changed for unknown reason,
-                    //        so we use the state to reset the x and y here.
-                    PropertyChanges {
-                        target: dragHandler.target
-                        x: x
-                        y: y
-                    }
-                }
-
-                TapHandler {
-                    acceptedButtons: Qt.RightButton
-                    onTapped: {
-                        showContextMenu(itemDelegate, model)
-                        baseLayer.focus = true
-                    }
-                }
-
-                DragHandler {
-                    id: dragHandler
-                    target: parent
-                    acceptedButtons: Qt.LeftButton
-                    dragThreshold: 1
+                MouseArea {
+                    id: mouseArea
+                    anchors.fill: parent
+                    
+                    acceptedButtons: Qt.LeftButton | Qt.RightButton
+                    drag.target: itemDelegate
                     // 当分类菜单打开时，禁用拖拽功能
                     enabled: !(ddeCategoryMenu.visible || alphabetCategoryPopup.visible)
-                    onActiveChanged: {
-                        if (active) {
-                            // We switch to use the `dndItem` to handle Drag event since that one will always exists.
-                            // If we use the current item, then if the item that provides the drag attached property
-                            // get destoryed (e.g. switch page or folder close caused destory), dropping at that moment
-                            // will cause a crash.
-                            dndItem.Drag.hotSpot = target.Drag.hotSpot
-                            dndItem.Drag.mimeData = target.Drag.mimeData
-
-                            parent.grabToImage(function(result) {
-                                dndItem.Drag.imageSource = result.url;
-                                dndItem.Drag.active = true
-                                dndItem.Drag.startDrag()
+
+                    onPressed: function (mouse) {
+                        if (mouse.button === Qt.LeftButton) {
+                            bg.visible = false
+                            itemDelegate.grabToImage(function(result) {
+                                itemDelegate.Drag.imageSource = result.url
+                                bg.visible = Qt.binding(function() {
+                                    return bg.ColorSelector.controlState === DTK.HoveredState
+                                })
                             })
                         }
                     }
-                }
-
-                background: Loader {
-                    active: !dragHandler.active
-                    sourceComponent: ItemBackground {
-                        focusPolicy: Qt.NoFocus
-                        implicitWidth: DStyle.Style.itemDelegate.width
-                        implicitHeight: Helper.windowed.listItemHeight
-                        button: itemDelegate
+                    onClicked: function (mouse) {
+                        if (mouse.button === Qt.RightButton) {
+                            showContextMenu(itemDelegate, model)
+                            baseLayer.focus = true
+                        } else {
+                            launchApp(desktopId)
+                        }
                     }
                 }
-
-                TapHandler {
-                    onTapped: {
-                        launchApp(desktopId)
-                    }
+                background: ItemBackground {
+                    id: bg
+                    implicitWidth: DStyle.Style.itemDelegate.width
+                    implicitHeight: Helper.windowed.listItemHeight
+                    button: itemDelegate
                 }
 
                 Keys.onReturnPressed: {