I'm opening this issue after discussing it in detail on stackexchange: http://stackoverflow.com/questions/13843604/calling-up-dockpanel-suites-autohidden-dockcontent-programmatically
As mentioned over on SO, this was introduced in the 2.6 release.
We need to find out a fix that solves both this and SF1849882. It takes time and we might defer it to release such as 2.9 or 3.0.
For reference, the breaking change was introduced by #10
After analyzing the code, I think we should keep the behavior as it is.
We should not attempt to show a "auto hide" content simply via the Show method, as they should be hidden.
Also we already have a workaround there to simply set this content as DockPanel.ActiveAutoHideContent, then it would be less urgent to modify the code base.