I've run into an issue where intermittantly a ToolWindowContainer is loosing its reference to the DockSite and I don't know why or how to get that reference back. I'm programmatically moving a single ToolWindow between two different ToolWindowContainers. One always has another ToolWindow in it's collection (no problem with this one) while the other only has at most the one. I'm using ToolWindowContainer.Windows.Add() and ToolWindowContainer.Windows.Remove() to faciliate the movement. I tried just using Attach() but that didn't work at all. The container that's loosing it DockSite reference is the one that can be empty. I'm not sure if this is a bug or if I'm just doing something incorrectly and would appreciate some guidance.