How to resize a dialogbar

[Bsbosa.com]

In my project I use many dialogbars allowing it to be docked and undocked.
I need to change the dialogbars size according to some runtime conditions and it works but,
when I dock or undock the dialog bar it restores the initial size or, when I dock another bar close to the resized bar, it consider the initial size and not the new one.

Does someone one know how to let dialogbar resize operation work properly ?

Thanks a lot !