I believe setting AutoScroll on a control (such as a Panel) will only show scrollbars if a contained control's is not fully visible within the Panel. However, setting AutoScroll on the control in the floating pane will not always work because the control in the floating pane is always resized to be the size of the floating pane. It doesn't necessarily mean that the control being resized has controls within it that need to be scrolled into view.

I would suggest adding the control you want to dock onto a Panel control instead. Set AutoScroll on that Panel to True and then dock the Panel control. The panel will be resized when it needs to be, but it will show scrollbars when the control within it doesn't fully fit.