lots of docs and examples

27 files changed, 495 insertions, 305 deletions

diff --git a/nexgb/Makefile b/nexgb/Makefile
index c70b01c..7ba1cb4 100644
--- a/nexgb/Makefile
+++ b/nexgb/Makefile
@@ -1,5 +1,6 @@
 # This Makefile is used by the developer. It is not needed in any way to build
 # a checkout of the XGB repository.
+# It will be useful, however, if you are hacking at the code generator.
 
 XPROTO=/usr/share/xcb
 
@@ -20,3 +21,8 @@ test:
 bench:
 	go test -run 'nomatch' -bench '.*' -cpu 1,2,6
 
+gofmt:
+	gofmt -w *.go xgbgen/*.go examples/*.go examples/*/*.go
+	colcheck xgbgen/*.go examples/*.go examples/*/*.go \
+					 auth.go conn.go cookie.go doc.go xgb.go xgb_help.go xgb_test.go
+
diff --git a/nexgb/doc.go b/nexgb/doc.go
new file mode 100644
index 0000000..b6c956f
--- /dev/null
+++ b/nexgb/doc.go
@@ -0,0 +1,152 @@
+/*
+Package XGB provides the X Go Binding, which is a low-level API to communicate
+with the core X protocol and many of the X extensions.
+
+It is *very* closely modeled on XCB, so that experience with XCB (or xpyb) is
+easily translatable to XGB. That is, it uses the same cookie/reply model
+and is thread safe. There are otherwise no major differences (in the API).
+
+Most uses of XGB typically fall under the realm of window manager and GUI kit
+development, but other applications (like pagers, panels, tilers, etc.) may
+also require XGB. Moreover, it is a near certainty that if you need to work
+with X, xgbutil will be of great use to you as well:
+https://github.com/BurntSushi/xgbutil
+
+Example
+
+This is an extremely terse example that demonstrates how to connect to X,
+create a window, listen to StructureNotify events and Key{Press,Release} 
+events, map the window, and print out all events received. An example with 
+accompanying documentation can be found in examples/create-window.
+
+	package main
+
+	import (
+		"fmt"
+		"github.com/BurntSushi/xgb"
+	)
+
+	func main() {
+		X, err := xgb.NewConn()
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+
+		wid, _ := X.NewId()
+		X.CreateWindow(X.DefaultScreen().RootDepth, wid, X.DefaultScreen().Root,
+			0, 0, 500, 500, 0,
+			xgb.WindowClassInputOutput, X.DefaultScreen().RootVisual,
+			xgb.CwBackPixel | xgb.CwEventMask,
+			[]uint32{ // values must be in the order defined by the protocol
+				0xffffffff,
+				xgb.EventMaskStructureNotify |
+				xgb.EventMaskKeyPress |
+				xgb.EventMaskKeyRelease})
+
+		X.MapWindow(wid)
+		for {
+			ev, xerr := X.WaitForEvent()
+			if ev == nil && xerr == nil {
+				fmt.Println("Both event and error are nil. Exiting...")
+				return
+			}
+
+			if ev != nil {
+				fmt.Printf("Event: %s\n", ev)
+			}
+			if xerr != nil {
+				fmt.Printf("Error: %s\n", xerr)
+			}
+		}
+	}
+
+Xinerama Example
+
+This is another small example that shows how to query Xinerama for geometry
+information of each active head. Accompanying documentation for this example
+can be found in examples/xinerama.
+
+	package main
+
+	import (
+		"fmt"
+		"log"
+		"github.com/BurntSushi/xgb"
+	)
+
+	func main() {
+		X, err := xgb.NewConn()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// Initialize the Xinerama extension.
+		// The appropriate 'Init' function must be run for *every*
+		// extension before any of its requests can be used.
+		err = X.XineramaInit()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		reply, err := X.XineramaQueryScreens().Reply()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		fmt.Printf("Number of heads: %d\n", reply.Number)
+		for i, screen := range reply.ScreenInfo {
+			fmt.Printf("%d :: X: %d, Y: %d, Width: %d, Height: %d\n",
+				i, screen.XOrg, screen.YOrg, screen.Width, screen.Height)
+		}
+	}
+
+Parallelism
+
+XGB can benefit greatly from parallelism due to its concurrent design. For
+evidence of this claim, please see the benchmarks in xgb_test.go.
+
+Tests
+
+xgb_test.go contains a number of contrived tests that stress particular corners
+of XGB that I presume could be problem areas. Namely: requests with no replies,
+requests with replies, checked errors, unchecked errors, sequence number
+wrapping, cookie buffer flushing (i.e., forcing a round trip every N requests
+made that don't have a reply), getting/setting properties and creating a window
+and listening to StructureNotify events.
+
+Code Generator
+
+Both XCB and xpyb use the same Python module (xcbgen) for a code generator. XGB
+(before this fork) used the same code generator as well, but in my attempt to
+add support for more extensions, I found the code generator extremely difficult
+to work with. Therefore, I re-wrote the code generator in Go. It can be found
+in its own sub-package, xgbgen, of xgb. My design of xgbgen includes a rough
+consideration that it could be used for other languages.
+
+What works
+
+I am reasonably confident that the core X protocol is in full working form. I've
+also tested the Xinerama and RandR extensions sparingly. Many of the other
+existing extensions have Go source generated (and are compilable) and are 
+included in this package, but I am currently unsure of their status. They 
+*should* work.
+
+What does not work
+
+XKB is the only extension that intentionally does not work, although I suspect
+that GLX also does not work (however, there is Go source code for GLX that
+compiles, unlike XKB). I don't currently have any intention of getting XKB 
+working, due to its complexity and my current mental incapacity to test it.
+
+There are so many functions
+
+Indeed. Everything below this initial overview is useful insomuch as your
+browser's "Find" feature is useful. The following list of types and functions
+should act as a reference to the Go representation of a request, type or reply
+of something you *already know about*. To search the following list in hopes
+of attaining understanding is a quest in folly. For understanding, please see
+the X Protocol Reference Manual: http://goo.gl/aMd2e
+
+*/
+package xgb
diff --git a/nexgb/examples/atom.go b/nexgb/examples/atom.go
deleted file mode 100644
index 2cb7132..0000000
--- a/nexgb/examples/atom.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package main
-
-import (
-	// "fmt" 
-	"log"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func init() {
-	log.SetFlags(0)
-}
-
-func main() {
-	X, err := xgb.NewConn()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	aname := "_NET_ACTIVE_WINDOW"
-	atom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
-	if err != nil {
-		log.Fatal(err)
-	}
-	log.Printf("%d", atom.Atom)
-}
-
diff --git a/nexgb/examples/create-window/main.go b/nexgb/examples/create-window/main.go
new file mode 100644
index 0000000..6996f37
--- /dev/null
+++ b/nexgb/examples/create-window/main.go
@@ -0,0 +1,98 @@
+// Example create-window shows how to create a window, map it, resize it,
+// and listen to structure and key events (i.e., when the window is resized
+// by the window manager, or when key presses/releases are made when the
+// window has focus). The events are printed to stdout.
+package main
+
+import (
+	"fmt"
+
+	"github.com/BurntSushi/xgb"
+)
+
+func main() {
+	X, err := xgb.NewConn()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	// Any time a new resource (i.e., a window, pixmap, graphics context, etc.)
+	// is created, we need to generate a resource identifier with NewId.
+	wid, _ := X.NewId()
+
+	// CreateWindow takes a boatload of parameters.
+	X.CreateWindow(X.DefaultScreen().RootDepth, wid, X.DefaultScreen().Root,
+		0, 0, 500, 500, 0,
+		xgb.WindowClassInputOutput, X.DefaultScreen().RootVisual,
+		0, []uint32{})
+
+	// This call to ChangeWindowAttributes could be factored out and
+	// included with the above CreateWindow call, but it is left here for
+	// instructive purposes. It tells X to send us events when the 'structure'
+	// of the window is changed (i.e., when it is resized, mapped, unmapped,
+	// etc.) and when a key press or a key release has been made when the
+	// window has focus.
+	// We also set the 'BackPixel' to white so that the window isn't butt ugly.
+	X.ChangeWindowAttributes(wid,
+		xgb.CwBackPixel|xgb.CwEventMask,
+		[]uint32{ // values must be in the order defined by the protocol
+			0xffffffff,
+			xgb.EventMaskStructureNotify |
+				xgb.EventMaskKeyPress |
+				xgb.EventMaskKeyRelease})
+
+	// MapWindow makes the window we've created appear on the screen.
+	// We demonstrated the use of a 'checked' request here.
+	// A checked request is a fancy way of saying, "do error handling
+	// synchronously." Namely, if there is a problem with the MapWindow request,
+	// we'll get the error *here*. If we were to do a normal unchecked
+	// request (like the above CreateWindow and ChangeWindowAttributes
+	// requests), then we would only see the error arrive in the main event
+	// loop.
+	//
+	// Typically, checked requests are useful when you need to make sure they
+	// succeed. Since they are synchronous, they incur a round trip cost before
+	// the program can continue, but this is only going to be noticeable if
+	// you're issuing tons of requests in succession.
+	//
+	// Note that requests without replies are by default unchecked while
+	// requests *with* replies are checked by default.
+	err = X.MapWindowChecked(wid).Check()
+	if err != nil {
+		fmt.Printf("Checked Error for mapping window %d: %s\n", wid, err)
+	} else {
+		fmt.Printf("Map window %d successful!\n", wid)
+	}
+
+	// This is an example of an invalid MapWindow request and what an error
+	// looks like.
+	err = X.MapWindowChecked(0).Check()
+	if err != nil {
+		fmt.Printf("Checked Error for mapping window 0x1: %s\n", err)
+	} else { // neva
+		fmt.Printf("Map window 0x1 successful!\n")
+	}
+
+	// Start the main event loop.
+	for {
+		// WaitForEvent either returns an event or an error and never both.
+		// If both are nil, then something went wrong and the loop should be
+		// halted.
+		//
+		// An error can only be seen here as a response to an unchecked
+		// request.
+		ev, xerr := X.WaitForEvent()
+		if ev == nil && xerr == nil {
+			fmt.Println("Both event and error are nil. Exiting...")
+			return
+		}
+
+		if ev != nil {
+			fmt.Printf("Event: %s\n", ev)
+		}
+		if xerr != nil {
+			fmt.Printf("Error: %s\n", xerr)
+		}
+	}
+}
diff --git a/nexgb/examples/doc.go b/nexgb/examples/doc.go
new file mode 100644
index 0000000..80ea5b7
--- /dev/null
+++ b/nexgb/examples/doc.go
@@ -0,0 +1,21 @@
+/*
+Package examples contains a few different use cases of XGB, like creating
+a window, reading properties, and querying for information about multiple
+heads using the Xinerama or RandR extensions.
+
+If you're looking to get started quickly, I recommend checking out the
+create-window example first. It is the most documented and probably covers
+some of the more common bare bones cases of creating windows and responding
+to events.
+
+If you're looking to query information about your window manager,
+get-active-window is a start. However, to do anything extensive requires
+a lot of boiler plate. To that end, I'd recommend use of my higher level
+library, xgbutil: https://github.com/BurntSushi/xgbutil
+
+There are also examples of using the Xinerama and RandR extensions, if you're
+interested in querying information about your active heads. In RandR's case,
+you can also reconfigure your heads, but the example doesn't cover that.
+
+*/
+package documentation
diff --git a/nexgb/examples/get-active-window/main.go b/nexgb/examples/get-active-window/main.go
new file mode 100644
index 0000000..e90563c
--- /dev/null
+++ b/nexgb/examples/get-active-window/main.go
@@ -0,0 +1,57 @@
+// Example get-active-window reads the _NET_ACTIVE_WINDOW property of the root
+// window and uses the result (a window id) to get the name of the window.
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/BurntSushi/xgb"
+)
+
+func main() {
+	X, err := xgb.NewConn()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the window id of the root window.
+	root := X.DefaultScreen().Root
+
+	// Get the atom id (i.e., intern an atom) of "_NET_ACTIVE_WINDOW".
+	aname := "_NET_ACTIVE_WINDOW"
+	activeAtom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the atom id (i.e., intern an atom) of "_NET_WM_NAME".
+	aname = "_NET_WM_NAME"
+	nameAtom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the actual value of _NET_ACTIVE_WINDOW.
+	// Note that 'reply.Value' is just a slice of bytes, so we use an
+	// XGB helper function, 'Get32', to pull an unsigned 32-bit integer out
+	// of the byte slice. We then convert it to an X resource id so it can
+	// be used to get the name of the window in the next GetProperty request.
+	reply, err := X.GetProperty(false, root, activeAtom.Atom,
+		xgb.GetPropertyTypeAny, 0, (1<<32)-1).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+	windowId := xgb.Id(xgb.Get32(reply.Value))
+	fmt.Printf("Active window id: %X\n", windowId)
+
+	// Now get the value of _NET_WM_NAME for the active window.
+	// Note that this time, we simply convert the resulting byte slice,
+	// reply.Value, to a string.
+	reply, err = X.GetProperty(false, windowId, nameAtom.Atom,
+		xgb.GetPropertyTypeAny, 0, (1<<32)-1).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Active window name: %s\n", string(reply.Value))
+}
diff --git a/nexgb/examples/property.go b/nexgb/examples/property.go
deleted file mode 100644
index 45144c7..0000000
--- a/nexgb/examples/property.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package main
-
-import (
-	"log"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func init() {
-	log.SetFlags(0)
-}
-
-func get32(buf []byte) uint32 {
-	v := uint32(buf[0])
-	v |= uint32(buf[1]) << 8
-	v |= uint32(buf[2]) << 16
-	v |= uint32(buf[3]) << 24
-	return v
-}
-
-func main() {
-	X, err := xgb.NewConn()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	root := X.DefaultScreen().Root
-
-	aname := "_NET_ACTIVE_WINDOW"
-	atom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	reply, err := X.GetProperty(false, root, atom.Atom,
-		xgb.GetPropertyTypeAny, 0, (1<<32)-1).Reply()
-	if err != nil {
-		log.Fatal(err)
-	}
-	log.Printf("%X", get32(reply.Value))
-}
diff --git a/nexgb/examples/randr.go b/nexgb/examples/randr.go
deleted file mode 100644
index 064856d..0000000
--- a/nexgb/examples/randr.go
+++ /dev/null
@@ -1,48 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func main() {
-	X, _ := xgb.NewConn()
-
-	err := X.RegisterExtension("randr")
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	resources, err := X.RandrGetScreenResources(X.DefaultScreen().Root).Reply()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	for _, output := range resources.Outputs {
-		info, err := X.RandrGetOutputInfo(output, 0).Reply()
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		bestMode := info.Modes[0]
-		for _, mode := range resources.Modes {
-			if mode.Id == uint32(bestMode) {
-				fmt.Printf("Width: %d, Height: %d\n", mode.Width, mode.Height)
-			}
-		}
-	}
-
-	fmt.Println("\n")
-
-	for _, crtc := range resources.Crtcs {
-		info, err := X.RandrGetCrtcInfo(crtc, 0).Reply()
-		if err != nil {
-			log.Fatal(err)
-		}
-		fmt.Printf("X: %d, Y: %d, Width: %d, Height: %d\n",
-			info.X, info.Y, info.Width, info.Height)
-	}
-}
-
diff --git a/nexgb/examples/randr/main.go b/nexgb/examples/randr/main.go
new file mode 100644
index 0000000..5c56609
--- /dev/null
+++ b/nexgb/examples/randr/main.go
@@ -0,0 +1,84 @@
+// Example randr uses the randr protocol to get information about the active
+// heads. It also listens for events that are sent when the head configuration
+// changes. Since it listens to events, you'll have to manually kill this
+// process when you're done (i.e., ctrl+c.)
+//
+// While this program is running, if you use 'xrandr' to reconfigure your
+// heads, you should see event information dumped to standard out.
+//
+// For more information, please see the RandR protocol spec:
+// http://www.x.org/releases/X11R7.6/doc/randrproto/randrproto.txt
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/BurntSushi/xgb"
+)
+
+func main() {
+	X, _ := xgb.NewConn()
+
+	// Every extension must be initialized before it can be used.
+	err := X.RandrInit()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Gets the current screen resources. Screen resources contains a list
+	// of names, crtcs, outputs and modes, among other things.
+	resources, err := X.RandrGetScreenResources(X.DefaultScreen().Root).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Iterate through all of the outputs and show some of their info.
+	for _, output := range resources.Outputs {
+		info, err := X.RandrGetOutputInfo(output, 0).Reply()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		bestMode := info.Modes[0]
+		for _, mode := range resources.Modes {
+			if mode.Id == uint32(bestMode) {
+				fmt.Printf("Width: %d, Height: %d\n", mode.Width, mode.Height)
+			}
+		}
+	}
+
+	fmt.Println("\n")
+
+	// Iterate through all of the crtcs and show some of their info.
+	for _, crtc := range resources.Crtcs {
+		info, err := X.RandrGetCrtcInfo(crtc, 0).Reply()
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Printf("X: %d, Y: %d, Width: %d, Height: %d\n",
+			info.X, info.Y, info.Width, info.Height)
+	}
+
+	// Tell RandR to send us events. (I think these are all of them, as of 1.3.)
+	err = X.RandrSelectInputChecked(X.DefaultScreen().Root,
+		xgb.RandrNotifyMaskScreenChange|
+			xgb.RandrNotifyMaskCrtcChange|
+			xgb.RandrNotifyMaskOutputChange|
+			xgb.RandrNotifyMaskOutputProperty).Check()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Listen to events and just dump them to standard out.
+	// A more involved approach will have to read the 'U' field of
+	// RandrNotifyEvent, which is a union (really a struct) of type
+	// RanrNotifyDataUnion.
+	for {
+		ev, err := X.WaitForEvent()
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Println(ev)
+	}
+}
diff --git a/nexgb/examples/seq-nowrap.go b/nexgb/examples/seq-nowrap.go
deleted file mode 100644
index 994a07b..0000000
--- a/nexgb/examples/seq-nowrap.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func main() {
-	X, _ := xgb.NewConn()
-
-	for i := 1; i <= 1<<16 + 10; i++ {
-		X.NoOperation()
-		// fmt.Printf("%d. No-Op\n", i) 
-	}
-
-	aname := "_NET_ACTIVE_WINDOW"
-
-	for i := 1; i <= 10; i++ {
-		atom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
-		if err != nil {
-			fmt.Println(err)
-		} else {
-			fmt.Printf("%d. Sequence: %d, Atom: %d\n",
-				i, atom.Sequence, atom.Atom)
-		}
-	}
-}
-
diff --git a/nexgb/examples/seq-wrap.go b/nexgb/examples/seq-wrap.go
deleted file mode 100644
index b5bc834..0000000
--- a/nexgb/examples/seq-wrap.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func main() {
-	X, _ := xgb.NewConn()
-
-	aname := "_NET_ACTIVE_WINDOW"
-
-	for i := 1; i <= 1<<16 + 10; i++ {
-		atom, err := X.InternAtom(true, uint16(len(aname)), aname).Reply()
-		if err != nil {
-			fmt.Println(err)
-		} else {
-			fmt.Printf("%d. Sequence: %d, Atom: %d\n",
-				i, atom.Sequence, atom.Atom)
-		}
-	}
-}
-
diff --git a/nexgb/examples/window.go b/nexgb/examples/window.go
deleted file mode 100644
index 68fe27b..0000000
--- a/nexgb/examples/window.go
+++ /dev/null
@@ -1,61 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func main() {
-	X, err := xgb.NewConn()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	wid, _ := X.NewId()
-	X.CreateWindow(X.DefaultScreen().RootDepth, wid, X.DefaultScreen().Root,
-		0, 0, 500, 500, 0,
-		xgb.WindowClassInputOutput, X.DefaultScreen().RootVisual,
-		0, []uint32{})
-	X.ChangeWindowAttributes(wid, xgb.CwEventMask | xgb.CwBackPixel,
-		[]uint32{0xffffffff, xgb.EventMaskKeyPress | xgb.EventMaskKeyRelease})
-
-	err = X.MapWindowChecked(wid).Check()
-	if err != nil {
-		fmt.Printf("Checked Error for mapping window %d: %s\n", wid, err)
-	} else {
-		fmt.Printf("Map window %d successful!\n", wid)
-	}
-
-	err = X.MapWindowChecked(0x1).Check()
-	if err != nil {
-		fmt.Printf("Checked Error for mapping window 0x1: %s\n", err)
-	} else {
-		fmt.Printf("Map window 0x1 successful!\n")
-	}
-
-	for {
-		ev, xerr := X.WaitForEvent()
-		if ev == nil && xerr == nil {
-			log.Fatal("Both event and error are nil. Exiting...")
-		}
-
-		if ev != nil {
-			fmt.Printf("Event: %s\n", ev)
-		}
-		if xerr != nil {
-			fmt.Printf("Error: %s\n", xerr)
-		}
-
-		if xerr == nil {
-			geom, err := X.GetGeometry(0x1).Reply()
-			if err != nil {
-				fmt.Printf("Geom Error: %#v\n", err)
-			} else {
-				fmt.Printf("Geometry: %#v\n", geom)
-			}
-		}
-	}
-}
-
diff --git a/nexgb/examples/xinerama.go b/nexgb/examples/xinerama.go
deleted file mode 100644
index 7fe9984..0000000
--- a/nexgb/examples/xinerama.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-
-	"github.com/BurntSushi/xgb"
-)
-
-func main() {
-	X, _ := xgb.NewConn()
-
-	err := X.RegisterExtension("xinerama")
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	reply, err := X.XineramaQueryScreens().Reply()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	fmt.Printf("Xinerama number: %d\n", reply.Number)
-	for i, screen := range reply.ScreenInfo {
-		fmt.Printf("%d :: X: %d, Y: %d, Width: %d, Height: %d\n",
-			i, screen.XOrg, screen.YOrg, screen.Width, screen.Height)
-	}
-}
-
diff --git a/nexgb/examples/xinerama/main.go b/nexgb/examples/xinerama/main.go
new file mode 100644
index 0000000..ec7f46a
--- /dev/null
+++ b/nexgb/examples/xinerama/main.go
@@ -0,0 +1,39 @@
+// Example xinerama shows how to query the geometry of all active heads.
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/BurntSushi/xgb"
+)
+
+func main() {
+	X, err := xgb.NewConn()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Initialize the Xinerama extension.
+	// The appropriate 'Init' function must be run for *every*
+	// extension before any of its requests can be used.
+	err = X.XineramaInit()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Issue a request to get the screen information.
+	reply, err := X.XineramaQueryScreens().Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// reply.Number is the number of active heads, while reply.ScreenInfo
+	// is a slice of XineramaScreenInfo containing the rectangle geometry
+	// of each head.
+	fmt.Printf("Number of heads: %d\n", reply.Number)
+	for i, screen := range reply.ScreenInfo {
+		fmt.Printf("%d :: X: %d, Y: %d, Width: %d, Height: %d\n",
+			i, screen.XOrg, screen.YOrg, screen.Width, screen.Height)
+	}
+}
diff --git a/nexgb/xgb.go b/nexgb/xgb.go
index 581b8fa..c9a265f 100644
--- a/nexgb/xgb.go
+++ b/nexgb/xgb.go
@@ -1,9 +1,3 @@
-// Copyright 2009 The XGB Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// The XGB package implements the X11 core protocol.
-// It is based on XCB: http://xcb.freedesktop.org/
 package xgb
 
 import (
diff --git a/nexgb/xgb_test.go b/nexgb/xgb_test.go
index 9665164..b70ff5e 100644
--- a/nexgb/xgb_test.go
+++ b/nexgb/xgb_test.go
@@ -45,8 +45,8 @@ func init() {
 // Tests
 /******************************************************************************/
 
-// TestSynchronousError purposefully causes a BadLength error in an
-// InternAtom request, and checks it synchronously.
+// TestSynchronousError purposefully causes a BadWindow error in a
+// MapWindow request, and checks it synchronously.
 func TestSynchronousError(t *testing.T) {
 	err := X.MapWindowChecked(0).Check() // resource id 0 is always invalid
 	if err == nil {
@@ -205,7 +205,7 @@ func TestWindowEvents(t *testing.T) {
 // BenchmarkInternAtomsGood shows how many requests with replies
 // *should* be sent and gathered from the server. Namely, send as many
 // requests as you can at once, then go back and gather up all the replies.
-// More importantly, this approach can exploit parallelism better when
+// More importantly, this approach can exploit parallelism when
 // GOMAXPROCS > 1.
 // Run with `go test -run 'nomatch' -bench '.*' -cpu 1,2,6` if you have
 // multiple cores to see the improvement that parallelism brings.
diff --git a/nexgb/xgbgen/context.go b/nexgb/xgbgen/context.go
index 35dd37e..f1762d3 100644
--- a/nexgb/xgbgen/context.go
+++ b/nexgb/xgbgen/context.go
@@ -86,7 +86,7 @@ func (c *Context) Morph(xmlBytes []byte) {
 		c.Putln("case err != nil:")
 		c.Putln("return err")
 		c.Putln("case !reply.Present:")
-		c.Putln("return newError(\"No extension named %s could be found on " +
+		c.Putln("return newError(\"No extension named %s could be found on "+
 			"on the server.\")", xname)
 		c.Putln("}")
 		c.Putln("")
diff --git a/nexgb/xgbgen/field.go b/nexgb/xgbgen/field.go
index 4452408..7c83f1a 100644
--- a/nexgb/xgbgen/field.go
+++ b/nexgb/xgbgen/field.go
@@ -220,7 +220,7 @@ func (f *ExprField) Initialize(p *Protocol) {
 // integers. The mask specifies which kinds of values are in the list.
 // (i.e., See ConfigureWindow, CreateWindow, ChangeWindowAttributes, etc.)
 type ValueField struct {
-	Parent interface{}
+	Parent   interface{}
 	MaskType Type
 	MaskName string
 	ListName string
@@ -247,7 +247,7 @@ func (f *ValueField) Size() Size {
 	listSize := newExpressionSize(&Function{
 		Name: "pad",
 		Expr: &BinaryOp{
-			Op: "*",
+			Op:    "*",
 			Expr1: &Value{v: 4},
 			Expr2: &PopCount{
 				Expr: &Function{
diff --git a/nexgb/xgbgen/go_error.go b/nexgb/xgbgen/go_error.go
index 0222289..9e01042 100644
--- a/nexgb/xgbgen/go_error.go
+++ b/nexgb/xgbgen/go_error.go
@@ -133,7 +133,7 @@ func (e *ErrorCopy) ImplementsError(c *Context) {
 func ErrorFieldString(c *Context, fields []Field, errName string) {
 	c.Putln("fieldVals := make([]string, 0, %d)", len(fields))
 	c.Putln("fieldVals = append(fieldVals, \"NiceName: \" + err.NiceName)")
-	c.Putln("fieldVals = append(fieldVals, " +
+	c.Putln("fieldVals = append(fieldVals, "+
 		"sprintf(\"Sequence: %s\", err.Sequence))", "%d")
 	for _, field := range fields {
 		switch field.(type) {
diff --git a/nexgb/xgbgen/go_event.go b/nexgb/xgbgen/go_event.go
index ce54e19..f55e26f 100644
--- a/nexgb/xgbgen/go_event.go
+++ b/nexgb/xgbgen/go_event.go
@@ -165,7 +165,7 @@ func (e *EventCopy) Write(c *Context) {
 func EventFieldString(c *Context, fields []Field, evName string) {
 	c.Putln("fieldVals := make([]string, 0, %d)", len(fields))
 	if evName != "KeymapNotify" {
-		c.Putln("fieldVals = append(fieldVals, " +
+		c.Putln("fieldVals = append(fieldVals, "+
 			"sprintf(\"Sequence: %s\", v.Sequence))", "%d")
 	}
 	for _, field := range fields {
@@ -177,7 +177,8 @@ func EventFieldString(c *Context, fields []Field, evName string) {
 			case *Base:
 			case *Resource:
 			case *TypeDef:
-			default: continue
+			default:
+				continue
 			}
 
 			switch field.SrcType() {
diff --git a/nexgb/xgbgen/go_list.go b/nexgb/xgbgen/go_list.go
index 41cfb76..ad859bb 100644
--- a/nexgb/xgbgen/go_list.go
+++ b/nexgb/xgbgen/go_list.go
@@ -107,4 +107,3 @@ func (f *ListField) Write(c *Context, prefix string) {
 			f.XmlName(), f.Type)
 	}
 }
-
diff --git a/nexgb/xgbgen/go_request_reply.go b/nexgb/xgbgen/go_request_reply.go
index 451667f..a9e624d 100644
--- a/nexgb/xgbgen/go_request_reply.go
+++ b/nexgb/xgbgen/go_request_reply.go
@@ -71,14 +71,14 @@ func (r *Request) ReadReply(c *Context) {
 	c.Putln("// Waits and reads reply data from request %s", r.SrcName())
 	c.Putln("func (cook %s) Reply() (*%s, error) {",
 		r.CookieName(), r.ReplyTypeName())
-		c.Putln("buf, err := cook.reply()")
-		c.Putln("if err != nil {")
-		c.Putln("return nil, err")
-		c.Putln("}")
-		c.Putln("if buf == nil {")
-		c.Putln("return nil, nil")
-		c.Putln("}")
-		c.Putln("return %s(buf), nil", r.ReplyName())
+	c.Putln("buf, err := cook.reply()")
+	c.Putln("if err != nil {")
+	c.Putln("return nil, err")
+	c.Putln("}")
+	c.Putln("if buf == nil {")
+	c.Putln("return nil, nil")
+	c.Putln("}")
+	c.Putln("return %s(buf), nil", r.ReplyName())
 	c.Putln("}")
 	c.Putln("")
 
@@ -107,7 +107,7 @@ func (r *Request) ReadReply(c *Context) {
 
 func (r *Request) WriteRequest(c *Context) {
 	writeSize := func() {
-		c.Putln("Put16(buf[b:], uint16(size / 4)) "+
+		c.Putln("Put16(buf[b:], uint16(size / 4)) " +
 			"// write request size in 4-byte units")
 		c.Putln("b += 2")
 		c.Putln("")
diff --git a/nexgb/xgbgen/go_union.go b/nexgb/xgbgen/go_union.go
index 9f339af..73e85f7 100644
--- a/nexgb/xgbgen/go_union.go
+++ b/nexgb/xgbgen/go_union.go
@@ -139,4 +139,3 @@ func (u *Union) WriteListSize(c *Context) {
 	c.Putln("}")
 	c.Putln("")
 }
-
diff --git a/nexgb/xgbgen/protocol.go b/nexgb/xgbgen/protocol.go
index e01bc17..83dde14 100644
--- a/nexgb/xgbgen/protocol.go
+++ b/nexgb/xgbgen/protocol.go
@@ -38,4 +38,3 @@ func (p *Protocol) Initialize() {
 func (p *Protocol) isExt() bool {
 	return strings.ToLower(p.Name) != "xproto"
 }
-
diff --git a/nexgb/xgbgen/request_reply.go b/nexgb/xgbgen/request_reply.go
index c7a4cf8..4daa4ac 100644
--- a/nexgb/xgbgen/request_reply.go
+++ b/nexgb/xgbgen/request_reply.go
@@ -13,9 +13,9 @@ type Request struct {
 	srcName string // The Go name of this request.
 	xmlName string // The XML name of this request.
 	Opcode  int
-	Combine bool // Not currently used.
+	Combine bool    // Not currently used.
 	Fields  []Field // All fields in the request.
-	Reply   *Reply // A reply, if one exists for this request.
+	Reply   *Reply  // A reply, if one exists for this request.
 }
 
 // Initialize creates the proper Go source name for this request.
diff --git a/nexgb/xgbgen/translation.go b/nexgb/xgbgen/translation.go
index 592c152..e4d81bc 100644
--- a/nexgb/xgbgen/translation.go
+++ b/nexgb/xgbgen/translation.go
@@ -339,7 +339,7 @@ func (x *XMLField) Translate(parent interface{}) Field {
 		}
 	case "valueparam":
 		return &ValueField{
-			Parent: parent,
+			Parent:   parent,
 			MaskType: newTranslation(x.ValueMaskType),
 			MaskName: x.ValueMaskName,
 			ListName: x.ValueListName,
diff --git a/nexgb/xgbgen/xml.go b/nexgb/xgbgen/xml.go
index df21433..440d0a8 100644
--- a/nexgb/xgbgen/xml.go
+++ b/nexgb/xgbgen/xml.go
@@ -17,11 +17,11 @@ type XML struct {
 
 	// Types for all top-level elements.
 	// First are the simple ones.
-	Imports     XMLImports     `xml:"import"`
-	Enums       []*XMLEnum       `xml:"enum"`
-	Xids        []*XMLXid        `xml:"xidtype"`
-	XidUnions   []*XMLXid        `xml:"xidunion"`
-	TypeDefs    []*XMLTypeDef    `xml:"typedef"`
+	Imports     XMLImports      `xml:"import"`
+	Enums       []*XMLEnum      `xml:"enum"`
+	Xids        []*XMLXid       `xml:"xidtype"`
+	XidUnions   []*XMLXid       `xml:"xidunion"`
+	TypeDefs    []*XMLTypeDef   `xml:"typedef"`
 	EventCopies []*XMLEventCopy `xml:"eventcopy"`
 	ErrorCopies []*XMLErrorCopy `xml:"errorcopy"`
 
@@ -93,21 +93,21 @@ type XMLErrorCopy struct {
 }
 
 type XMLStruct struct {
-	Name   string    `xml:"name,attr"`
+	Name   string      `xml:"name,attr"`
 	Fields []*XMLField `xml:",any"`
 }
 
 type XMLUnion struct {
-	Name   string    `xml:"name,attr"`
+	Name   string      `xml:"name,attr"`
 	Fields []*XMLField `xml:",any"`
 }
 
 type XMLRequest struct {
-	Name    string    `xml:"name,attr"`
-	Opcode  int       `xml:"opcode,attr"`
-	Combine bool      `xml:"combine-adjacent,attr"`
+	Name    string      `xml:"name,attr"`
+	Opcode  int         `xml:"opcode,attr"`
+	Combine bool        `xml:"combine-adjacent,attr"`
 	Fields  []*XMLField `xml:",any"`
-	Reply   *XMLReply `xml:"reply"`
+	Reply   *XMLReply   `xml:"reply"`
 }
 
 type XMLReply struct {
@@ -115,15 +115,15 @@ type XMLReply struct {
 }
 
 type XMLEvent struct {
-	Name       string    `xml:"name,attr"`
-	Number     int       `xml:"number,attr"`
-	NoSequence bool      `xml:"no-sequence-number,attr"`
+	Name       string      `xml:"name,attr"`
+	Number     int         `xml:"number,attr"`
+	NoSequence bool        `xml:"no-sequence-number,attr"`
 	Fields     []*XMLField `xml:",any"`
 }
 
 type XMLError struct {
-	Name   string    `xml:"name,attr"`
-	Number int       `xml:"number,attr"`
+	Name   string      `xml:"name,attr"`
+	Number int         `xml:"number,attr"`
 	Fields []*XMLField `xml:",any"`
 }