Remove Obsolete Classes/Methods

Author: ghost1372

dev/DevWinUI.Controls/Common/NavigationView/SettingsNavigationAttach.cs

@@ -1,5 +1,4 @@
 using Microsoft.UI.Windowing;
-using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls.Primitives;
 using Microsoft.UI.Xaml.Shapes;
 

dev/DevWinUI.Controls/Controls/WindowedContentDialog/WindowedContentDialog.cs

@@ -4,7 +4,7 @@
 
 namespace DevWinUI;
 
-public class FilePicker
+public partial class FilePicker
 {
     private IntPtr hwnd;
     public FilePicker(IntPtr hwnd)

dev/DevWinUI/Common/Picker/FilePicker.cs

@@ -3,7 +3,7 @@
 
 namespace DevWinUI;
 
-public class FolderPicker
+public partial class FolderPicker
 {
     private IntPtr hwnd;
     public FolderPicker(IntPtr hwnd)

dev/DevWinUI/Common/Picker/FolderPicker.cs

@@ -4,7 +4,7 @@
 
 namespace DevWinUI;
 
-public class SavePicker
+public partial class SavePicker
 {
     private IntPtr hwnd;
     public SavePicker(IntPtr hwnd)