As you have already found out, there are two options for positioning the RadDock controls in a RadDockZone - horizontal and vertical. The layout that you want to achieve requires putting every RadDock column in a wrapper with left float. Nevertheless, the RadDockZone supports only dock controls in its content so using wrappers for the groups of RadDocks will break their functionality.
A possible approach for achieving your scenario is to use a separate RadDockZone for every column of RadDocks and to implement the desired logic for moving the dock controls via their client-side API. I have attached a sample page that demonstrates such solution. If it meets your requirements, you can use it or you can incorporate your logic instead. Note that this is a customization of the default behavior of RadDock and may cause problems in some scenarios, as it is not fully tested.
All the best,
the Telerik team
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