To reproduce:
- add a dock with ToolWindow and DocumentWindow
- set the following properties:
        ToolWindow1.TabStrip.SizeInfo.SizeMode = Telerik.WinControls.UI.Docking.SplitPanelSizeMode.Absolute
        ToolWindow1.TabStrip.MaximumSize = New Size(94, 400)
        ToolWindow1.TabStrip.SizeInfo.AbsoluteSize = New Size(94, 400)
        ToolWindow1.DefaultFloatingSize = New Size(94, 400)

- Run the app, change the ToolWindow DockState to floating from context menu in the ToolWindow caption
- re-dock the ToolWindow => its sizi is not 94,400 and its SizeMode and AbsoluteSize properties have different values

If you perform the same scenario, but make the ToolWindow floating with drag and drop not with the context menu, everything works fine correctly.

WORKAROUND:
    Private Sub RadDock1_DockStateChanging(sender As Object, e As Telerik.WinControls.UI.Docking.DockStateChangingEventArgs)
        If e.NewWindow Is ToolWindow1 AndAlso e.NewDockState = Telerik.WinControls.UI.Docking.DockState.Docked Then
            e.NewWindow.TabStrip.SizeInfo.SizeMode = Telerik.WinControls.UI.Docking.SplitPanelSizeMode.Absolute
            e.NewWindow.TabStrip.MaximumSize = New Size(94, 400)
            e.NewWindow.TabStrip.SizeInfo.AbsoluteSize = New Size(94, 400)
            e.NewWindow.DefaultFloatingSize = New Size(94, 400)
        End If
    End Sub