It doesn't have to be so big. Modern GUI toolkits are just really bad about keeping their sizes down for some reason. I wrote my own personal GUI toolkit on to

It doesn't have to be so big. Modern GUI toolkits are just really bad about keeping their sizes down for some reason. I wrote my own personal GUI toolkit on top of OpenGL/GLFW for developing special purpose editors (for gamedev), and the resulting executables plus required shared libraries and resources (minus system libraries like libGL that shouldn't be distributed directly with the application) are only about a megabyte or two total. That includes a full blown custom scripting language interpreter, resizable rich text widget with bold/italics/color support + optional text wrapping and scrollbars, JSON parser and serializer, vector math library, a basic image loader and saver for several formats (using stb plus a little custom code for a few less common formats), various routines for software manipulation of surfaces (e.g. drawing lines, triangles, alpha blending images, and so on)... written in C++, with debugging info turned on, and using templates where appropriate. (It'd be even smaller if I stripped debug info and packed the whole thing into one executable.) I'm developing it on Linux, but I could rebuild it for Windows (and probably Mac) without too much effort. I don't know what the hell the GUI libraries are doing to get so big.