still messing around with the problem with "ingore minsize"
I tried to build a "brute force workaround" by disabeling the user to resize the panel when in AutoHide.
I set FixedSplitters (just to check) to true on my docking manager.
This works so far as if with that setting the splitter can no longer be moved.
After setting the left panel to "AutoHide" - I can change it's size :(
To disable AutoHide is not possible since some users have "small" screens where they have to AutoHide to get enough working space in the right panel.
By the - this would bring me to Forms.SplitContaier - which does all the things without errors / bugs --- except the "AutoHide".
It seems to me, as if the DockingManager has a lot of serious problems.
By playing around with it just for a few days I failed to build a very simple layout (Explorer) with some simple settings (MinSize, no ContextMenu, AutoHide).
Since my project has to be finished - it looks as if it is not really possible with this control.
I guess to create my own thing based on "SplitContainer" is less work than trying to overcome the bugs.