FBUI, or FrameBufferUI, is a small, in-kernel graphical user interface for Linux. It works only with kernel 2.6.9, although I've gotten it partially working with 2.6.31.
A summary of its key features:
* It is very small, about 50kB.
* It lives inside the Linux kernel, which places a natural limit on GUI bloat.
* It permits multiple programs to share the framebuffer by letting each have graphical windows.
* Each program may have multiple windows.
* Windows may overlap, and be moved, resized, raised, lowered etc.
* There can be windows on each virtual console.
* Program interaction with FBUI is via a small set of system calls (ioctls).
* Drawing primitives now support transparency.
* It includes a small library libfbui to make using FBUI easier, and it includes an image-manipulation library and a font library.
Item FBUI 0.11.0(in kB) X-Windows / XFree86 (in kB)
Core software ~50 1710
Library software ~30 1370 (just Xlib; required)
Panel-style window manager program 46½ (fbpm / static link) not available
Conventional window manager 41 (fbwm* / static link) 145 (twm / dynamic link)
Terminal emulator program 73 (fbterm / static link) 247 (xterm / dynamic link)
Analog clock program size 43½ (fbclock / static link) 29 (xclock / dynamic link)
Simple calculator program size 43½ (fbcalc / static link) ? (xcalc / dynamic link)
JPEG/TIFF viewer 60 (fbview / static link) 962 (xv / dynamic link)