Thank you for the writing.
The RadMessageBoxForm uses the Clipboard that requires an STA. So the solution in this case is to set the ApartmentState
of your thread to be STA. For example:
ThreadStart job2 =
Thread thread2 =
RadMessageBoxForm form =
form.DialogResult = DialogResult.No;
form.RightToLeft = RightToLeft.No;
form.StartPosition = FormStartPosition.CenterParent;
form.ButtonsConfiguration = MessageBoxButtons.YesNo;
form.DefaultButton = MessageBoxDefaultButton.Button1;
There's lots of code in Windows that requires an STA. Notable examples are the Clipboard, Drag & Drop and the shell dialogs (like OpenFileDialog). The UI thread of a WPF or Windows Forms project should always be STA, as does any thread that creates a window.
I hope this helps. Let me know if you have additional questions.
the Telerik team