Thank you for contacting us. In response to the issues you raised:
1. Lock property
This property locks the control bounds, i.e. the control cannot be sized nor repositioned. The content of the control, however, can be changed. See for example the behavior of Microsoft's ToolStrip when locked.
2. "Add New Row/Column" feature
You are correct. The behavior you're observing is inappropriate and annoying. We will be making changes to this functionality in the future and we will be fixing the way this specific feature is implemented to make it easier to use.
We appreciate your feedback. Please, don't hesitate to contact us again, if we could be of any service.
the Telerik team