CorelDRAW Graphics Suite X4 :: Expanded Layers In Object Manager

I have the object manager pane visible at the right of my screen. It shows the layers and status of those layers in my drawing. It has the + icon that allows each layer to be expanded to show every line in that layer. The trouble I am having is that each an every time I do something in the drawing to a line it prompts the Object Manager list to expand to the full list of lines.  Clicking the - icon closes this down to just the layer name.

Thing is, how do I stop it expanding the the list to the line level of detail in the first place. I rarely need that level of detail and waste lots of time closing the view down.