I'm seeing a weird problem with a Ext.window.Window which just contains a tab panel with two tabs (each is a Ext.panel.Panel).

When I select one of the tabs, the window is no longer movable. If I dont select one of the tabs the window moves fine.

I'm attempting to reduce the code down for easy debugging, but so far there is very little in the code other than the tab handling.

Any ideas what might be causing this? Works fine in 4.0.7.