xgbutil is a utility library designed to work with the X Go Binding. This project's main goal is to make various X related tasks easier. For example, binding keys, using the EWMH or ICCCM specs with the window manager, moving/resizing windows, assigning function callbacks to particular events, drawing images to a window, etc.
xgbutil attempts to be thread safe, but it has not been completely tested in this regard. In general, the X event loop implemented in the xevent package is sequential. The idea is to be sequential by default, and let the user spawn concurrent code at their discretion. (i.e., the complexity of making the main event loop generally concurrent is vast.)
You may sleep safely at night by assuming that XGB is thread safe, though.
To start using xgbutil, you should have at least a passing familiarity with X. Your first stop should be the examples directory.
go get github.com/BurntSushi/xgbutil
XGB is the main dependency. Use of the xgraphics packages requires graphics-go and freetype-go.
XGB project URL: https://github.com/BurntSushi/xgb
go get github.com/BurntSushi/xgbutil/_examples/window-name-sizes "$GOPATH"/bin/window-name-sizes
The output will be a list of names of all top-level windows and their geometry including window manager decorations. (Assuming your window manager supports some basic EWMH properties.)
https://godoc.org/github.com/BurntSushi/xgbutil
There are several examples in the examples directory covering common use cases. They are heavily documented and should run out of the box.
An older project of mine, xpybutil, served as inspiration for xgbutil. If you want to use Python, xpybutil should help quite a bit. Please note though, that at this point, xgbutil provides a lot more functionality and is much better documented.
xpybutil project URL: https://github.com/BurntSushi/xpybutil