switch from XDrawPoint to XPutPixel and XPutImage
only Escape keypress should break from loop
giving SDL a try (simple "Hello, world" program)

My use of Xlib has been fairly unrewarding. I am uncertain about what
whether my event loop is remotely "legal", and every variation I've
tried to improve performance of painting a bitmap has been met with
unsatisfying results. As I had not yet had a stroke of luck (nor had
I received a clue from someone with some Xlib experience), I decided
to take a step back and reconsider my options.

First, I looked at XCB (X protocol C-language Binding), but the code
examples I found did not work with the versions of the libraries.
After a bit of exploration, I did not feel like XCB would be very more
fruitful; I did not even have anything worth committing to this repo.

I found that some is publishing an SDL companion to Homemaid Hero for
linux users, and they have decided to use SDL:

http://davidgow.net/handmadepenguin/

The Simple Directmedia Layer is higher level than Xlib, but not too
far away from the spirit of Handmade Hero, I think. While I still
think Xlib is closer in sprit to "no libraries, just what the OS
provides" the Win32 APIs seem richer than Xlib, but perhaps similar
to SDL.

So, now I will take a walk down SDL lane and see if this is any easier
to wrap my head around. I should also be able to get some extra help
by looking at the "Handmade Penguin" site, a distinct advantage over
funbling around with the Xlib API docs. We shall see!
create a simple SDL window and event loop
flicker on resize
Okay, SDL looks like the way forward
convert to SDL
extract window resizing to function
extract stretch_virtual_to_offscreen function
only bother resize when we get a resize event
separate image creation from window drawing
unify duplicate structures, improve naming
tidy comments a bit
exit when escape key is pressed
note the swith to SDL in README