Why am I getting this error:“Cross-thread operation not valid: Control lbFolders accessed from a thread other than the thread it was created on.”?

Question

This is baffling me, maybe somebody can shine the light of education on my ignorance. This is in a C# windows app. I am accessing the contents of a listbox from a thread.

Answer 1

The Count property of SelectedItems is not thread-safe, so you can't use it cross-thread.