问题
The MSDN page for the ShowWithoutActivation method - here - on a Form state that ToolStripItems are windowless.
What does it mean for a control to be windowless? What purpose do they serve? How can I make my own Windowless controls?
回答1:
In underlying Windows architecture, a Control is basically a borderless Window. They are 90% the same thing.
A ToolStripItem, on the other hand, does not derive from Control. It does not draw itself, it does not have a Window handle or a message queue. A ToolStripItem is just a class that functions as an organizational extension of the ToolStrip. The ToolStrip forwards many messages and events to the ToolStripItems.
The purpose of this is to improve performance and allow better transparency.
来源：https://stackoverflow.com/questions/11145387/windowless-controls