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