There is currently a command set_layout, which is a nice and flexible way of splitting the window. Unfortunately, there doesn't appear to be a get_layout yet to determine the current layout. Is there any other way of determining this information? If not, consider this a feature request.
The use case is a keyboard shortcut for the SublimeREPL plugin. What I'd like to do is to take the current layout when I press the key to open the REPL, halve all the tab group heights and add a new tab group in the bottom half of the screen. Once I have the cols, rows and cells information of the current layout this should be trivial.