DOCKS AND DIALOGS, stacking?

[sedmont]

In docking dialog windows, is there a way to stack dialog windows on top of each other rather than have them turn into columns running the whole length of gimp?  With the "undo" window  or the layers window, having a long column is good, but with other windows I just need a box shaped window, not a long column, and would like to stack the boxes on top of one another. Would also like to be able to lengthen or shorten a dialog window even if it is docked. How does one do that? Can't seem to find documentation on this. 

Thanks in advance for any assistance..