wow, works great.
i made a paint programm without much gui stuff where i made sure that i can draw fluently, like in mspaint. i could merge that with your paint project and make a nice little drawing application, like krita or paint tool sai.
or, i just started to write my own mesh display programm so i can quickly change and display a mesh with custom properties to create a model editor. i could merge this with your builder project and maybe even a add a ray tracer.
or, or, or...
i just never got around on how to make something like the scroll bar you use in your builder app. (try googleing for this and find stuff not related to web-dev, jQuery and css)
i will give you a special place in the credits of my video editor. i can use the zoom functionality from your paint program to zoom the video in my editor and use your scroll bar to scroll on the timeline, on the source file panel and so much more.
thanks for sharing your amazing work