Qt's Cross-Platform Functionality

[winston2020]

Cool, thanks.

[Brandybuck]

I believe there are only a dozen files that are platform specific, out of hundreds. In terms of the GUI, there is low level code to draw windows, process events, etc. Everything else is built on top of that. For example, to draw a button on the screen, it will use Windows GDI, or OSX Quartz, or X11 Xlib. I don't know about Quartz, but GDI and Xlib have very similar drawing concepts (pens, brushes, contexts, etc).