/cc @nigeltao

I'm happy to take a patch a la https://golang.org/doc/contribute.html but I can't repro the bug myself so can't be sure that whatever I write will fix anything.

Out of curiousity, what sort of X11 configuration leads to this situation?

It's a pretty bog standard Ubuntu 14/04 config with the Nvidia 340 binary drivers. The examples used to work when I tested right after Go 1.4 got released, but not anymore, and I really couldn't say what has changed on my system since then.

Anyhow, when I debugged this issue, EGL returned visual id 0x27 while the default is 0x21, as reported by xdpyinfo:

  number of visuals:    228
  default visual id:  0x21
  visual:
    visual id:    0x21
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
(...)
  visual:
    visual id:    0x27
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits

There's probably more to it, but they look the same.

Adding the colormap is straightforward, but I ran into another issue with the basic example that crashes somewhere in gl.DrawArrays(), so I want to investigate this further before submitting a patch (I don't see how adding a true color colormap could cause this, but one never knows). The sprite example runs fine though.

CL submitted: https://go-review.googlesource.com/6260

For future reference, people affected by this issue will get the following error message:

X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  1 (X_CreateWindow)

Also the problem I was experiencing with the basic example is unrelated. It was caused by #9534.

This was fixed by https://go-review.googlesource.com/#/c/6260/ but the CL description said issue #9997 instead of #9997.