When you are using a coded step there is no need to create a new Settings or Manager objects. You can simply use the existing ones. Also, there is no need to start or stop the Dialog Monitor, Test Studio will do that for you. The following code should be enough to handle the Save File dialog with a coded step:
SaveAsDialog saveDlg = SaveAsDialog.CreateSaveAsDialog(Manager.ActiveApplication, DialogButton.SAVE,
I have created a simple WPF application with Save File dialog and as you can see in this video
. I was able to handle it both ways, via a regular recorded step and via a coded step. I have attached the sample project for your reference.
If you continue to have difficulty a local repro is necessary. Can you provide a copy of your WPF app, or ask your developers to create a small sample app that demonstrates the issue? If you deem that information too sensitive for a public forum, please attach it a support ticket (which is confidential) and reference this thread.
the Telerik team