I tried the demo and there seems to be a lot of visual issues.
First when you click the play button at the bottom, the menus are empty of icons, then the icons appear for a split second outside (as though they have just been loaded in the middle of the frame), then they appear in the menus.
When you click the ui icon on the desktop the same thing happens with the text. Also you can see the text moving as the window resizes itself with easing. By opening and closing them quicky it becomes quite noticeable.
I think what you have done is great, but i don't think based on this demo it can be used for a professional game in its current form.