Swapping control into a different parent

Colleagues,

What I'm trying to achieve is kind of an undocking behavior, where a control can undock from one form and float in a different form. My code is based on a working reference design* - DockExtender[^] **. Unfortunately, I ran into a problem. I’m getting an exception when I try to assign a different parent form to the control.

private void FloatPanel()
{
   // this method resides in the new parent form for the control to float in
   // m_ctrlContainer control, which will be swapped into a floating form
   m_ctrlContainer.Parent = this;   // throws exception "Collection is read only."
}

The same exception occurs if I call this.Controlls.Add(m_ctrlContainer). It looks like the parent is in a state where controls can’t be added. What can I do to add controls to it?

Any suggestion, insight or reference is really appreciated!

- Nick

* EDIT: I'm re-creating the DockExtender (reference design). It's an exercise rather than attempt to reuse a docking framework as-is.

** EDIT: Parallel thread in the DockExtender article discussion[^].

Tags: Windows Forms, Controls, Exceptions