File dialogs and message box service

[tibel]

https://docs.microsoft.com/en-us/uwp/api/windows.ui.popups.messagedialog https://docs.microsoft.com/en-us/windows/uwp/files/quickstart-using-file-and-folder-pickers https://docs.microsoft.com/en-us/uwp/api/windows.storage.pickers.fileopenpicker https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.controls.contentdialog