InvokeRequired and ToolStripStatusLabel

This is because ToolStripItem (base for those two causing an error) is a Component and not a Control. Try calling your extension method on the tool strip that owns them and adjust your delegate methods.

I'd like to add up to the accepted solution. You can get the control from the component by using the GetCurrentParent method of the ToolStripStatusLabel.

Instead of doing toolStripStatusLabel1.InvokeIfRequired, do toolStripStatusLabel1.GetCurrentParent().InvokeIfRequired