Thanks for the reply, I think I found my problem though. It had to do with having an axes which was a child of an HBox that was embedded in a bunch of VBox & HBox's and setting the selectedChild to a tab where the axes wasn't. I was able to fix it by making sure the VBox & HBox's units were set to normalized and the position set to [0 0 1 1].
Here is an example though to illustrate. The first time you run it you'll notice that 'Page 2' appears empty. If you run it again with the last line commented out then it appears to work fine. If you run it one last time with the last line uncommented and the first HBox with the units as normalized and position [0 0 1 1] (uncomment line 7, comment line 8) then you can start on the first Page and still have Page 2 work properly.
Awesome Toolbox! I've enjoyed looking through the code to help me in my own OOP work in MATLAB.
I found a bug with using Axes and the TabPanel. If you have an Axes on a tab and you switch to another that has a 'spacing' where the axes is in the other tab then you can see the axes. I don't know if this is related to the clipping bug w/ UIPANELS or not but I thought I would put it out there.
@Sohil - You can only specify top and bottom TabPosition in GLT.
If you are using R2014b then you can now make use of the fully supported uitab and uitabgroup which allow you to set the TabLocation property to top, bottom, left or right.