System.Threading.ThreadstateException

Question

Hi, I'm developing an adding for office powerpoint application. I'm trying to display a description of the object(Customized object) currently dropped on the powerpoint slide in design mode(Design mode of the powerpoint). When i click on my addin the related object description will be displayed on a tabbed window as the first tabpage.

There is a button on the tab page, and when i click on it i need the description to get copied to windows clipboard. I tried this using clipboardclass it throws the following exception, System.Threading.ThreadstateException {"Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it."}

Code for clipboard: Clipboard.Clear() Clipboard.SetText(lblObjectID.Text)

I searched the net for a solution and got couple of answers like, 1. Put [STAThread] in the main function 2. Thread.CurrentThread.SetApartmentState(ApartmentState.STA) Immediately before your call to SetDataObject.

But I'm not sure where to put the 1st one and the 2nd option didn't work. Can anyone help me please. Thanks.

Answer 1

WinForms are STA by default. Are you creating another thread or using a BackgroundWorker? Run this code to determine what mode you're in:

MessageBox.Show(System.Threading.Thread.CurrentThread.GetApartmentState().ToString())

Edit:

But maybe you could also try using this command before calling the clipboard functions:

Application.OleRequired()