Essentially the workspace.ShowErrorMessage and workspace.ShowWarningMessage APIs create notifications that automatically dismiss. This can be unfortunate, as they are easily missed. It would be nice if developers had a away to indicate that these notifications required explicit dismissal from the end user.
Are you sure workspace.ShowErrorMessage auto-dismisses? I just tried it out and it opens a modal that dims the whole background and is centered in the window and has an OK button. I can’t even dismiss it by hitting ESC or clicking off it. I must click the OK button to make it go away. It does not go away on its own.