Look at the property FixedPanel. You can then indicate whether you want to install Panel1or Panel2. Three options:
No (this is the default value)
Indicates that neither SplitContainer.Panel1, SplitContainer.Panel2 is fixed. The Control.Resize event affects both panels.
Panel1
, SplitContainer.Panel1 . Control.Resize SplitContainer.Panel2.
2
, SplitContainer.Panel2 . Control.Resize SplitContainer.Panel1.