Fantastic submission. I had to recently write my own code for drag/drop with checkbox trees and it was a headache to say the least. I think I'll be moving over to using this straight away. Please push the developers to get this in to the product ASAP!
If you could now just submit a similar quality submission to wrap a Java table to fix all of uitables shortfalls that would be fantastic as I can then ditch my own code for this.
I think you need a proper properties panel on the side rather than the ribbon. Something along the lines of the inspect().
I write my GUIs in code, also because I do not like GUIDE, and this appdesigner is a potential game changer. However, it needs to give control over the properties of the elements and the Ribbon is a waste of space and mouse movements and does not display in a concise way all the possibilities.
Also, why not allow people to contribute to the project, through Github?
Otherwise, keep up the good work :)
@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.