the last parameter of XChangeProperty is the number of elements.. and when the element format is 32.. the element is "long" so we have 5 long elements here.

Yes this seems confusing as on mac+linux Long is either 32 or 64bits depending on the architecture, but this is how the X11 protocol is defined. Thus 5 is the correct value for the nelts here.  Not 5 or 10 depending on the architecture.

More info on the confusion https://bugs.freedesktop.org/show_bug.cgi?id=16802

docs/README-directfb.md

@@ -0,0 +1,107 @@
+DirectFB
+========
+
+Supports:
+
+- Hardware YUV overlays
+- OpenGL - software only
+- 2D/3D accelerations (depends on directfb driver)
+- multiple displays
+- windows
+
+What you need:
+
+* DirectFB 1.0.1, 1.2.x, 1.3.0
+* Kernel-Framebuffer support: required: vesafb, radeonfb .... 
+* Mesa 7.0.x	   - optional for OpenGL
+
+/etc/directfbrc
+
+This file should contain the following lines to make
+your joystick work and avoid crashes:
+------------------------
+disable-module=joystick
+disable-module=cle266
+disable-module=cyber5k
+no-linux-input-grab
+------------------------
+
+To disable to use x11 backend when DISPLAY variable is found use
+
+export SDL_DIRECTFB_X11_CHECK=0
+
+To disable the use of linux input devices, i.e. multimice/multikeyboard support,
+use
+
+export SDL_DIRECTFB_LINUX_INPUT=0
+
+To use hardware accelerated YUV-overlays for YUV-textures, use:
+
+export SDL_DIRECTFB_YUV_DIRECT=1
+
+This is disabled by default. It will only support one 
+YUV texture, namely the first. Every other YUV texture will be
+rendered in software.
+
+In addition, you may use (directfb-1.2.x)
+
+export SDL_DIRECTFB_YUV_UNDERLAY=1
+
+to make the YUV texture an underlay. This will make the cursor to
+be shown.
+
+Simple Window Manager
+=====================
+
+The driver has support for a very, very basic window manager you may
+want to use when running with "wm=default". Use
+
+export SDL_DIRECTFB_WM=1
+
+to enable basic window borders. In order to have the window title rendered,
+you need to have the following font installed:
+
+/usr/share/fonts/truetype/freefont/FreeSans.ttf
+
+OpenGL Support
+==============
+
+The following instructions will give you *software* OpenGL. However this
+works at least on all directfb supported platforms.
+
+As of this writing 20100802 you need to pull Mesa from git and do the following:
+
+------------------------
+git clone git://anongit.freedesktop.org/git/mesa/mesa
+cd mesa 
+git checkout 2c9fdaf7292423c157fc79b5ce43f0f199dd753a
+------------------------
+
+Edit configs/linux-directfb so that the Directories-section looks like
+------------------------
+# Directories
+SRC_DIRS     = mesa glu 
+GLU_DIRS     = sgi
+DRIVER_DIRS  = directfb
+PROGRAM_DIRS = 
+------------------------
+
+make linux-directfb
+make
+
+echo Installing - please enter sudo pw.
+
+sudo make install INSTALL_DIR=/usr/local/dfb_GL
+cd src/mesa/drivers/directfb
+make
+sudo make install INSTALL_DIR=/usr/local/dfb_GL
+------------------------
+
+To run the SDL - testprograms:
+
+export SDL_VIDEODRIVER=directfb
+export LD_LIBRARY_PATH=/usr/local/dfb_GL/lib
+export LD_PRELOAD=/usr/local/dfb_GL/libGL.so.7
+
+./testgl
+