chore: use default system qtquick controls style

gallery/Main.qml

@@ -3,7 +3,8 @@ import Qt.labs.platform
 import Gallery
 import DesignSystem
 import QtQuick.Layouts
-import QtQuick.Controls.Basic
+import QtQuick.Controls.Fusion
+// import QtQuick.Controls.macOS
 import QtQuick.Dialogs
 
 AppWindow {
@@ -76,7 +77,7 @@ AppWindow {
                 text: "The document has been modified."
             }
 
-            AppComboBox {
+            ComboBox {
                 model: ListModel {
                     id: model
                     ListElement {
@@ -97,7 +98,7 @@ AppWindow {
                 }
             }
 
-            AppTextField {
+            TextField {
                 placeholderText: qsTr("Enter name")
             }
 
@@ -119,41 +120,29 @@ AppWindow {
             AppWarning {
                 Layout.fillWidth: true
             }
-
-            AppMenu {
-                id: menu
-
-                Action {
-                    text: qsTr("Tool Bar")
-                    checkable: true
-                }
-                Action {
-                    text: qsTr("Side Bar")
-                    checkable: true
-                    checked: true
-                }
-                Action {
-                    text: qsTr("Status Bar")
-                    checkable: true
-                    checked: true
-                }
-
-                MenuSeparator {}
-
-                Action {
-                    text: "Hello"
-                }
-
-                // NOTE: MenuItem is not recommended as it isn't consistent with the menu theming. Please use Action until a fix is made.
-            }
             AppIcon {
                 source: "qrc:/live.flowy/imports/DesignSystem/icons/sidebar-duotone.svg"
             }
-            AppSecondaryButton {
-                onClicked: menu.open()
-                text: "Open menu"
-            }
+            Button {
+              id: fileButton
+              text: "File"
+              onClicked: menu.open()
 
+              Menu {
+                id: menu
+                y: fileButton.height
+
+                MenuItem {
+                  text: "New..."
+                }
+                MenuItem {
+                  text: "Open..."
+                }
+                MenuItem {
+                  text: "Save"
+                }
+              }
+            }
             Row {
               AppText {
                 text: "duotone"