C# WinForms: How to set Main function STAThreadAttribute

Question

I get the following exception when calling saveFileDialog.ShowDialog() in a background thread:

Current thread must be set to single thr

Answer 1

On your MainForm:

if (this.InvokeRequired) { 
 this.Invoke(saveFileDialog.ShowDialog()); 
} else { 
 saveFileDialog.ShowDialog(); 
}

Or, if you will have other methods that need to be run from the UI thread:

  private void DoOnUIThread(MethodInvoker d) {
     if (this.InvokeRequired) { this.Invoke(d); } else { d(); }
  }

Then, call your method as such:

 DoOnUIThread(delegate() {
    saveFileDialog.ShowDialog();
 });