select problems

I have a document with thousands of objects. a few of them are layered. I am having some difficulty selecting some of the objects, notably the boxes that overlay the main document which have objects on top of them. Are objects that are not visible (behind) supposed to be selectable? The behavior seems a little erratic.

[arthur]

Yes, invisible objects could be selected. If you click for once, Editor will select the first layer, click twice, the second layer will be selected...