Here is a collection of samples I’ve written in the past few days to answer your questions from the MSDN forums, etc. I hope you find these helpful – keep the questions coming!
How can I intercept the mouse down on a ToolStripGrip?
How do I use Table layout with ToolStrip?
How can I clone a ToolStripMenuItem?
How can I use ToolStripManager.Merge?
How can I implement IDeviceContext?