diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..82cc409
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,8 @@
+language: go
+go:
+  - "1.9"
+install:
+  - make install-ci
+script:
+  - make ci
+
diff --git a/Gopkg.lock b/Gopkg.lock
index 46c38c7..d97ce89 100644
--- a/Gopkg.lock
+++ b/Gopkg.lock
@@ -51,7 +51,7 @@
 
 [[projects]]
   name = "github.com/stretchr/testify"
-  packages = ["assert"]
+  packages = ["assert","require"]
   revision = "69483b4bd14f5845b5a1e55bca19e954e827f1d0"
   version = "v1.1.4"
 
@@ -70,6 +70,6 @@
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "762af1e7e6510b65bbeaf64779b19184108aaa0e1279cc5f38ebb05f19e8a8a3"
+  inputs-digest = "6a8eca20c8e483ea61bcee8787af6d6cb4907b96a5ef90e80fbf37e013078c3b"
   solver-name = "gps-cdcl"
   solver-version = 1
diff --git a/Makefile b/Makefile
index d2e02f3..b6857bb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,43 @@
+
+GO_FILES := $(shell git ls-files | grep "\.go$$")
+
+PACKAGES := $(shell find $(GO_FILES) | xargs -n1 dirname | sed 's:^:./:'| uniq)
+
+.PHONY: test
 test:
 	go test ./...
 
+.PHONY: gofmt
+gofmt:
+	gofmt -e -s -l $(GO_FILES)
+
+.PHONY: govet
+govet:
+	go vet ./...
+
+.PHONY: golint
+golint:
+	golint $(PACKAGES)
+
+.PHONY: errcheck
+errcheck:
+	errcheck -ignoretests $(PACKAGES)
+
+.PHONY: lint
+lint: gofmt govet golint errcheck
+
+.PHONY: install
+install:
+	dep ensure
+
+.PHONY: install-ci
+install-ci:
+	go get -u github.com/golang/dep/cmd/dep github.com/golang/lint/golint github.com/kisielk/errcheck
+	dep ensure
+
+.PHONY: ci
+ci: test lint
+
 run/%: proofs/%
 	go run $(shell find $< -maxdepth 1 -name *.go -not -name *_test.go)
 
diff --git a/internal/cops/braille/braille.go b/internal/cops/braille/braille.go
index b6d64ca..b089c0f 100644
--- a/internal/cops/braille/braille.go
+++ b/internal/cops/braille/braille.go
@@ -62,7 +62,7 @@ func Draw(dst *display.Display, r image.Rectangle, src image.Image, sp image.Poi
 	DrawBitmap(dst, r, bits, sp, on)
 }
 
-// DrawBitmap
+// DrawBitmap FIXME
 func DrawBitmap(dst *display.Display, r image.Rectangle, src BitmapReader, sp image.Point, fg color.Color) {
 	w, h := r.Dx(), r.Dy()
 	for y := 0; y < h; y++ {
diff --git a/internal/cops/display/colors.go b/internal/cops/display/colors.go
index 9190e97..3996144 100644
--- a/internal/cops/display/colors.go
+++ b/internal/cops/display/colors.go
@@ -11,260 +11,260 @@ var Transparent = color.RGBA{}
 // the high intensity variants of the first 8 in more advanced ANSI terminals.
 // The next 6x6x6 colors are an RGB cube and the last 24 are shades of gray.
 var Colors = []color.RGBA{
-	color.RGBA{0, 0, 0, 255},
-	color.RGBA{128, 0, 0, 255},
-	color.RGBA{0, 128, 0, 255},
-	color.RGBA{128, 128, 0, 255},
-	color.RGBA{0, 0, 128, 255},
-	color.RGBA{128, 0, 128, 255},
-	color.RGBA{0, 128, 128, 255},
-	color.RGBA{192, 192, 192, 255},
-	color.RGBA{128, 128, 128, 255},
-	color.RGBA{255, 0, 0, 255},
-	color.RGBA{0, 255, 0, 255},
-	color.RGBA{255, 255, 0, 255},
-	color.RGBA{0, 0, 255, 255},
-	color.RGBA{255, 0, 255, 255},
-	color.RGBA{0, 255, 255, 255},
-	color.RGBA{255, 255, 255, 255},
-	color.RGBA{0, 0, 0, 255},
-	color.RGBA{0, 0, 95, 255},
-	color.RGBA{0, 0, 135, 255},
-	color.RGBA{0, 0, 175, 255},
-	color.RGBA{0, 0, 215, 255},
-	color.RGBA{0, 0, 255, 255},
-	color.RGBA{0, 95, 0, 255},
-	color.RGBA{0, 95, 95, 255},
-	color.RGBA{0, 95, 135, 255},
-	color.RGBA{0, 95, 175, 255},
-	color.RGBA{0, 95, 215, 255},
-	color.RGBA{0, 95, 255, 255},
-	color.RGBA{0, 135, 0, 255},
-	color.RGBA{0, 135, 95, 255},
-	color.RGBA{0, 135, 135, 255},
-	color.RGBA{0, 135, 175, 255},
-	color.RGBA{0, 135, 215, 255},
-	color.RGBA{0, 135, 255, 255},
-	color.RGBA{0, 175, 0, 255},
-	color.RGBA{0, 175, 95, 255},
-	color.RGBA{0, 175, 135, 255},
-	color.RGBA{0, 175, 175, 255},
-	color.RGBA{0, 175, 215, 255},
-	color.RGBA{0, 175, 255, 255},
-	color.RGBA{0, 215, 0, 255},
-	color.RGBA{0, 215, 95, 255},
-	color.RGBA{0, 215, 135, 255},
-	color.RGBA{0, 215, 175, 255},
-	color.RGBA{0, 215, 215, 255},
-	color.RGBA{0, 215, 255, 255},
-	color.RGBA{0, 255, 0, 255},
-	color.RGBA{0, 255, 95, 255},
-	color.RGBA{0, 255, 135, 255},
-	color.RGBA{0, 255, 175, 255},
-	color.RGBA{0, 255, 215, 255},
-	color.RGBA{0, 255, 255, 255},
-	color.RGBA{95, 0, 0, 255},
-	color.RGBA{95, 0, 95, 255},
-	color.RGBA{95, 0, 135, 255},
-	color.RGBA{95, 0, 175, 255},
-	color.RGBA{95, 0, 215, 255},
-	color.RGBA{95, 0, 255, 255},
-	color.RGBA{95, 95, 0, 255},
-	color.RGBA{95, 95, 95, 255},
-	color.RGBA{95, 95, 135, 255},
-	color.RGBA{95, 95, 175, 255},
-	color.RGBA{95, 95, 215, 255},
-	color.RGBA{95, 95, 255, 255},
-	color.RGBA{95, 135, 0, 255},
-	color.RGBA{95, 135, 95, 255},
-	color.RGBA{95, 135, 135, 255},
-	color.RGBA{95, 135, 175, 255},
-	color.RGBA{95, 135, 215, 255},
-	color.RGBA{95, 135, 255, 255},
-	color.RGBA{95, 175, 0, 255},
-	color.RGBA{95, 175, 95, 255},
-	color.RGBA{95, 175, 135, 255},
-	color.RGBA{95, 175, 175, 255},
-	color.RGBA{95, 175, 215, 255},
-	color.RGBA{95, 175, 255, 255},
-	color.RGBA{95, 215, 0, 255},
-	color.RGBA{95, 215, 95, 255},
-	color.RGBA{95, 215, 135, 255},
-	color.RGBA{95, 215, 175, 255},
-	color.RGBA{95, 215, 215, 255},
-	color.RGBA{95, 215, 255, 255},
-	color.RGBA{95, 255, 0, 255},
-	color.RGBA{95, 255, 95, 255},
-	color.RGBA{95, 255, 135, 255},
-	color.RGBA{95, 255, 175, 255},
-	color.RGBA{95, 255, 215, 255},
-	color.RGBA{95, 255, 255, 255},
-	color.RGBA{135, 0, 0, 255},
-	color.RGBA{135, 0, 95, 255},
-	color.RGBA{135, 0, 135, 255},
-	color.RGBA{135, 0, 175, 255},
-	color.RGBA{135, 0, 215, 255},
-	color.RGBA{135, 0, 255, 255},
-	color.RGBA{135, 95, 0, 255},
-	color.RGBA{135, 95, 95, 255},
-	color.RGBA{135, 95, 135, 255},
-	color.RGBA{135, 95, 175, 255},
-	color.RGBA{135, 95, 215, 255},
-	color.RGBA{135, 95, 255, 255},
-	color.RGBA{135, 135, 0, 255},
-	color.RGBA{135, 135, 95, 255},
-	color.RGBA{135, 135, 135, 255},
-	color.RGBA{135, 135, 175, 255},
-	color.RGBA{135, 135, 215, 255},
-	color.RGBA{135, 135, 255, 255},
-	color.RGBA{135, 175, 0, 255},
-	color.RGBA{135, 175, 95, 255},
-	color.RGBA{135, 175, 135, 255},
-	color.RGBA{135, 175, 175, 255},
-	color.RGBA{135, 175, 215, 255},
-	color.RGBA{135, 175, 255, 255},
-	color.RGBA{135, 215, 0, 255},
-	color.RGBA{135, 215, 95, 255},
-	color.RGBA{135, 215, 135, 255},
-	color.RGBA{135, 215, 175, 255},
-	color.RGBA{135, 215, 215, 255},
-	color.RGBA{135, 215, 255, 255},
-	color.RGBA{135, 255, 0, 255},
-	color.RGBA{135, 255, 95, 255},
-	color.RGBA{135, 255, 135, 255},
-	color.RGBA{135, 255, 175, 255},
-	color.RGBA{135, 255, 215, 255},
-	color.RGBA{135, 255, 255, 255},
-	color.RGBA{175, 0, 0, 255},
-	color.RGBA{175, 0, 95, 255},
-	color.RGBA{175, 0, 135, 255},
-	color.RGBA{175, 0, 175, 255},
-	color.RGBA{175, 0, 215, 255},
-	color.RGBA{175, 0, 255, 255},
-	color.RGBA{175, 95, 0, 255},
-	color.RGBA{175, 95, 95, 255},
-	color.RGBA{175, 95, 135, 255},
-	color.RGBA{175, 95, 175, 255},
-	color.RGBA{175, 95, 215, 255},
-	color.RGBA{175, 95, 255, 255},
-	color.RGBA{175, 135, 0, 255},
-	color.RGBA{175, 135, 95, 255},
-	color.RGBA{175, 135, 135, 255},
-	color.RGBA{175, 135, 175, 255},
-	color.RGBA{175, 135, 215, 255},
-	color.RGBA{175, 135, 255, 255},
-	color.RGBA{175, 175, 0, 255},
-	color.RGBA{175, 175, 95, 255},
-	color.RGBA{175, 175, 135, 255},
-	color.RGBA{175, 175, 175, 255},
-	color.RGBA{175, 175, 215, 255},
-	color.RGBA{175, 175, 255, 255},
-	color.RGBA{175, 215, 0, 255},
-	color.RGBA{175, 215, 95, 255},
-	color.RGBA{175, 215, 135, 255},
-	color.RGBA{175, 215, 175, 255},
-	color.RGBA{175, 215, 215, 255},
-	color.RGBA{175, 215, 255, 255},
-	color.RGBA{175, 255, 0, 255},
-	color.RGBA{175, 255, 95, 255},
-	color.RGBA{175, 255, 135, 255},
-	color.RGBA{175, 255, 175, 255},
-	color.RGBA{175, 255, 215, 255},
-	color.RGBA{175, 255, 255, 255},
-	color.RGBA{215, 0, 0, 255},
-	color.RGBA{215, 0, 95, 255},
-	color.RGBA{215, 0, 135, 255},
-	color.RGBA{215, 0, 175, 255},
-	color.RGBA{215, 0, 215, 255},
-	color.RGBA{215, 0, 255, 255},
-	color.RGBA{215, 95, 0, 255},
-	color.RGBA{215, 95, 95, 255},
-	color.RGBA{215, 95, 135, 255},
-	color.RGBA{215, 95, 175, 255},
-	color.RGBA{215, 95, 215, 255},
-	color.RGBA{215, 95, 255, 255},
-	color.RGBA{215, 135, 0, 255},
-	color.RGBA{215, 135, 95, 255},
-	color.RGBA{215, 135, 135, 255},
-	color.RGBA{215, 135, 175, 255},
-	color.RGBA{215, 135, 215, 255},
-	color.RGBA{215, 135, 255, 255},
-	color.RGBA{215, 175, 0, 255},
-	color.RGBA{215, 175, 95, 255},
-	color.RGBA{215, 175, 135, 255},
-	color.RGBA{215, 175, 175, 255},
-	color.RGBA{215, 175, 215, 255},
-	color.RGBA{215, 175, 255, 255},
-	color.RGBA{215, 215, 0, 255},
-	color.RGBA{215, 215, 95, 255},
-	color.RGBA{215, 215, 135, 255},
-	color.RGBA{215, 215, 175, 255},
-	color.RGBA{215, 215, 215, 255},
-	color.RGBA{215, 215, 255, 255},
-	color.RGBA{215, 255, 0, 255},
-	color.RGBA{215, 255, 95, 255},
-	color.RGBA{215, 255, 135, 255},
-	color.RGBA{215, 255, 175, 255},
-	color.RGBA{215, 255, 215, 255},
-	color.RGBA{215, 255, 255, 255},
-	color.RGBA{255, 0, 0, 255},
-	color.RGBA{255, 0, 95, 255},
-	color.RGBA{255, 0, 135, 255},
-	color.RGBA{255, 0, 175, 255},
-	color.RGBA{255, 0, 215, 255},
-	color.RGBA{255, 0, 255, 255},
-	color.RGBA{255, 95, 0, 255},
-	color.RGBA{255, 95, 95, 255},
-	color.RGBA{255, 95, 135, 255},
-	color.RGBA{255, 95, 175, 255},
-	color.RGBA{255, 95, 215, 255},
-	color.RGBA{255, 95, 255, 255},
-	color.RGBA{255, 135, 0, 255},
-	color.RGBA{255, 135, 95, 255},
-	color.RGBA{255, 135, 135, 255},
-	color.RGBA{255, 135, 175, 255},
-	color.RGBA{255, 135, 215, 255},
-	color.RGBA{255, 135, 255, 255},
-	color.RGBA{255, 175, 0, 255},
-	color.RGBA{255, 175, 95, 255},
-	color.RGBA{255, 175, 135, 255},
-	color.RGBA{255, 175, 175, 255},
-	color.RGBA{255, 175, 215, 255},
-	color.RGBA{255, 175, 255, 255},
-	color.RGBA{255, 215, 0, 255},
-	color.RGBA{255, 215, 95, 255},
-	color.RGBA{255, 215, 135, 255},
-	color.RGBA{255, 215, 175, 255},
-	color.RGBA{255, 215, 215, 255},
-	color.RGBA{255, 215, 255, 255},
-	color.RGBA{255, 255, 0, 255},
-	color.RGBA{255, 255, 95, 255},
-	color.RGBA{255, 255, 135, 255},
-	color.RGBA{255, 255, 175, 255},
-	color.RGBA{255, 255, 215, 255},
-	color.RGBA{255, 255, 255, 255},
-	color.RGBA{8, 8, 8, 255},
-	color.RGBA{18, 18, 18, 255},
-	color.RGBA{28, 28, 28, 255},
-	color.RGBA{38, 38, 38, 255},
-	color.RGBA{48, 48, 48, 255},
-	color.RGBA{58, 58, 58, 255},
-	color.RGBA{68, 68, 68, 255},
-	color.RGBA{78, 78, 78, 255},
-	color.RGBA{88, 88, 88, 255},
-	color.RGBA{98, 98, 98, 255},
-	color.RGBA{108, 108, 108, 255},
-	color.RGBA{118, 118, 118, 255},
-	color.RGBA{128, 128, 128, 255},
-	color.RGBA{138, 138, 138, 255},
-	color.RGBA{148, 148, 148, 255},
-	color.RGBA{158, 158, 158, 255},
-	color.RGBA{168, 168, 168, 255},
-	color.RGBA{178, 178, 178, 255},
-	color.RGBA{188, 188, 188, 255},
-	color.RGBA{198, 198, 198, 255},
-	color.RGBA{208, 208, 208, 255},
-	color.RGBA{218, 218, 218, 255},
-	color.RGBA{228, 228, 228, 255},
-	color.RGBA{238, 238, 238, 255},
+	{0, 0, 0, 255},
+	{128, 0, 0, 255},
+	{0, 128, 0, 255},
+	{128, 128, 0, 255},
+	{0, 0, 128, 255},
+	{128, 0, 128, 255},
+	{0, 128, 128, 255},
+	{192, 192, 192, 255},
+	{128, 128, 128, 255},
+	{255, 0, 0, 255},
+	{0, 255, 0, 255},
+	{255, 255, 0, 255},
+	{0, 0, 255, 255},
+	{255, 0, 255, 255},
+	{0, 255, 255, 255},
+	{255, 255, 255, 255},
+	{0, 0, 0, 255},
+	{0, 0, 95, 255},
+	{0, 0, 135, 255},
+	{0, 0, 175, 255},
+	{0, 0, 215, 255},
+	{0, 0, 255, 255},
+	{0, 95, 0, 255},
+	{0, 95, 95, 255},
+	{0, 95, 135, 255},
+	{0, 95, 175, 255},
+	{0, 95, 215, 255},
+	{0, 95, 255, 255},
+	{0, 135, 0, 255},
+	{0, 135, 95, 255},
+	{0, 135, 135, 255},
+	{0, 135, 175, 255},
+	{0, 135, 215, 255},
+	{0, 135, 255, 255},
+	{0, 175, 0, 255},
+	{0, 175, 95, 255},
+	{0, 175, 135, 255},
+	{0, 175, 175, 255},
+	{0, 175, 215, 255},
+	{0, 175, 255, 255},
+	{0, 215, 0, 255},
+	{0, 215, 95, 255},
+	{0, 215, 135, 255},
+	{0, 215, 175, 255},
+	{0, 215, 215, 255},
+	{0, 215, 255, 255},
+	{0, 255, 0, 255},
+	{0, 255, 95, 255},
+	{0, 255, 135, 255},
+	{0, 255, 175, 255},
+	{0, 255, 215, 255},
+	{0, 255, 255, 255},
+	{95, 0, 0, 255},
+	{95, 0, 95, 255},
+	{95, 0, 135, 255},
+	{95, 0, 175, 255},
+	{95, 0, 215, 255},
+	{95, 0, 255, 255},
+	{95, 95, 0, 255},
+	{95, 95, 95, 255},
+	{95, 95, 135, 255},
+	{95, 95, 175, 255},
+	{95, 95, 215, 255},
+	{95, 95, 255, 255},
+	{95, 135, 0, 255},
+	{95, 135, 95, 255},
+	{95, 135, 135, 255},
+	{95, 135, 175, 255},
+	{95, 135, 215, 255},
+	{95, 135, 255, 255},
+	{95, 175, 0, 255},
+	{95, 175, 95, 255},
+	{95, 175, 135, 255},
+	{95, 175, 175, 255},
+	{95, 175, 215, 255},
+	{95, 175, 255, 255},
+	{95, 215, 0, 255},
+	{95, 215, 95, 255},
+	{95, 215, 135, 255},
+	{95, 215, 175, 255},
+	{95, 215, 215, 255},
+	{95, 215, 255, 255},
+	{95, 255, 0, 255},
+	{95, 255, 95, 255},
+	{95, 255, 135, 255},
+	{95, 255, 175, 255},
+	{95, 255, 215, 255},
+	{95, 255, 255, 255},
+	{135, 0, 0, 255},
+	{135, 0, 95, 255},
+	{135, 0, 135, 255},
+	{135, 0, 175, 255},
+	{135, 0, 215, 255},
+	{135, 0, 255, 255},
+	{135, 95, 0, 255},
+	{135, 95, 95, 255},
+	{135, 95, 135, 255},
+	{135, 95, 175, 255},
+	{135, 95, 215, 255},
+	{135, 95, 255, 255},
+	{135, 135, 0, 255},
+	{135, 135, 95, 255},
+	{135, 135, 135, 255},
+	{135, 135, 175, 255},
+	{135, 135, 215, 255},
+	{135, 135, 255, 255},
+	{135, 175, 0, 255},
+	{135, 175, 95, 255},
+	{135, 175, 135, 255},
+	{135, 175, 175, 255},
+	{135, 175, 215, 255},
+	{135, 175, 255, 255},
+	{135, 215, 0, 255},
+	{135, 215, 95, 255},
+	{135, 215, 135, 255},
+	{135, 215, 175, 255},
+	{135, 215, 215, 255},
+	{135, 215, 255, 255},
+	{135, 255, 0, 255},
+	{135, 255, 95, 255},
+	{135, 255, 135, 255},
+	{135, 255, 175, 255},
+	{135, 255, 215, 255},
+	{135, 255, 255, 255},
+	{175, 0, 0, 255},
+	{175, 0, 95, 255},
+	{175, 0, 135, 255},
+	{175, 0, 175, 255},
+	{175, 0, 215, 255},
+	{175, 0, 255, 255},
+	{175, 95, 0, 255},
+	{175, 95, 95, 255},
+	{175, 95, 135, 255},
+	{175, 95, 175, 255},
+	{175, 95, 215, 255},
+	{175, 95, 255, 255},
+	{175, 135, 0, 255},
+	{175, 135, 95, 255},
+	{175, 135, 135, 255},
+	{175, 135, 175, 255},
+	{175, 135, 215, 255},
+	{175, 135, 255, 255},
+	{175, 175, 0, 255},
+	{175, 175, 95, 255},
+	{175, 175, 135, 255},
+	{175, 175, 175, 255},
+	{175, 175, 215, 255},
+	{175, 175, 255, 255},
+	{175, 215, 0, 255},
+	{175, 215, 95, 255},
+	{175, 215, 135, 255},
+	{175, 215, 175, 255},
+	{175, 215, 215, 255},
+	{175, 215, 255, 255},
+	{175, 255, 0, 255},
+	{175, 255, 95, 255},
+	{175, 255, 135, 255},
+	{175, 255, 175, 255},
+	{175, 255, 215, 255},
+	{175, 255, 255, 255},
+	{215, 0, 0, 255},
+	{215, 0, 95, 255},
+	{215, 0, 135, 255},
+	{215, 0, 175, 255},
+	{215, 0, 215, 255},
+	{215, 0, 255, 255},
+	{215, 95, 0, 255},
+	{215, 95, 95, 255},
+	{215, 95, 135, 255},
+	{215, 95, 175, 255},
+	{215, 95, 215, 255},
+	{215, 95, 255, 255},
+	{215, 135, 0, 255},
+	{215, 135, 95, 255},
+	{215, 135, 135, 255},
+	{215, 135, 175, 255},
+	{215, 135, 215, 255},
+	{215, 135, 255, 255},
+	{215, 175, 0, 255},
+	{215, 175, 95, 255},
+	{215, 175, 135, 255},
+	{215, 175, 175, 255},
+	{215, 175, 215, 255},
+	{215, 175, 255, 255},
+	{215, 215, 0, 255},
+	{215, 215, 95, 255},
+	{215, 215, 135, 255},
+	{215, 215, 175, 255},
+	{215, 215, 215, 255},
+	{215, 215, 255, 255},
+	{215, 255, 0, 255},
+	{215, 255, 95, 255},
+	{215, 255, 135, 255},
+	{215, 255, 175, 255},
+	{215, 255, 215, 255},
+	{215, 255, 255, 255},
+	{255, 0, 0, 255},
+	{255, 0, 95, 255},
+	{255, 0, 135, 255},
+	{255, 0, 175, 255},
+	{255, 0, 215, 255},
+	{255, 0, 255, 255},
+	{255, 95, 0, 255},
+	{255, 95, 95, 255},
+	{255, 95, 135, 255},
+	{255, 95, 175, 255},
+	{255, 95, 215, 255},
+	{255, 95, 255, 255},
+	{255, 135, 0, 255},
+	{255, 135, 95, 255},
+	{255, 135, 135, 255},
+	{255, 135, 175, 255},
+	{255, 135, 215, 255},
+	{255, 135, 255, 255},
+	{255, 175, 0, 255},
+	{255, 175, 95, 255},
+	{255, 175, 135, 255},
+	{255, 175, 175, 255},
+	{255, 175, 215, 255},
+	{255, 175, 255, 255},
+	{255, 215, 0, 255},
+	{255, 215, 95, 255},
+	{255, 215, 135, 255},
+	{255, 215, 175, 255},
+	{255, 215, 215, 255},
+	{255, 215, 255, 255},
+	{255, 255, 0, 255},
+	{255, 255, 95, 255},
+	{255, 255, 135, 255},
+	{255, 255, 175, 255},
+	{255, 255, 215, 255},
+	{255, 255, 255, 255},
+	{8, 8, 8, 255},
+	{18, 18, 18, 255},
+	{28, 28, 28, 255},
+	{38, 38, 38, 255},
+	{48, 48, 48, 255},
+	{58, 58, 58, 255},
+	{68, 68, 68, 255},
+	{78, 78, 78, 255},
+	{88, 88, 88, 255},
+	{98, 98, 98, 255},
+	{108, 108, 108, 255},
+	{118, 118, 118, 255},
+	{128, 128, 128, 255},
+	{138, 138, 138, 255},
+	{148, 148, 148, 255},
+	{158, 158, 158, 255},
+	{168, 168, 168, 255},
+	{178, 178, 178, 255},
+	{188, 188, 188, 255},
+	{198, 198, 198, 255},
+	{208, 208, 208, 255},
+	{218, 218, 218, 255},
+	{228, 228, 228, 255},
+	{238, 238, 238, 255},
 }
diff --git a/internal/cops/displaydraw/displaydraw.go b/internal/cops/displaydraw/displaydraw.go
index 860fabb..527481c 100644
--- a/internal/cops/displaydraw/displaydraw.go
+++ b/internal/cops/displaydraw/displaydraw.go
@@ -7,7 +7,9 @@ import (
 	"github.com/borkshop/bork/internal/cops/display"
 )
 
-func AsciiBox(d *display.Display, r image.Rectangle, fg, bg color.Color) {
+// ASCIIBox draws a box onto a display with given foreground and background
+// colors using ASCII "|" and "-", with "." and "'' for corners.
+func ASCIIBox(d *display.Display, r image.Rectangle, fg, bg color.Color) {
 	r.Max = r.Max.Sub(image.Point{1, 1})
 	for y := r.Min.Y + 1; y < r.Max.Y; y++ {
 		d.Set(r.Min.X, y, "|", fg, bg)
@@ -23,15 +25,18 @@ func AsciiBox(d *display.Display, r image.Rectangle, fg, bg color.Color) {
 	d.Set(r.Max.X, r.Max.Y, "'", fg, bg)
 }
 
-func SpaceBox(d *display.Display, r image.Rectangle, m image.Point, c color.Color) {
+// SpaceBox draws a border on the interior of the given rectangle.
+// The border shows a color filled cells, but copying the screen will reveal
+// "|" and "-" characters with the same foreground and background.
+func SpaceBox(d *display.Display, r image.Rectangle, b image.Point, c color.Color) {
 	for y := r.Min.Y; y < r.Max.Y; y++ {
-		for x := 0; x < m.X; x++ {
+		for x := 0; x < b.X; x++ {
 			d.Set(r.Min.X+x, y, "|", c, c)
 			d.Set(r.Max.X-x-1, y, "|", c, c)
 		}
 	}
 	for x := r.Min.X; x < r.Max.X; x++ {
-		for y := 0; y < m.Y; y++ {
+		for y := 0; y < b.Y; y++ {
 			d.Set(x, r.Min.Y+y, "-", c, c)
 			d.Set(x, r.Max.Y-y-1, "-", c, c)
 		}
diff --git a/internal/cops/examples/borkart/main.go b/internal/cops/examples/borkart/main.go
index ae8b2ee..acd9025 100644
--- a/internal/cops/examples/borkart/main.go
+++ b/internal/cops/examples/borkart/main.go
@@ -12,16 +12,21 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 
 	term := terminal.New(os.Stdout.Fd())
-	defer term.Restore()
-	term.SetRaw()
+	defer func() {
+		err = term.Restore()
+	}()
+	err = term.SetRaw()
+	if err != nil {
+		return err
+	}
 
 	bounds, err := term.Bounds()
 	if err != nil {
@@ -72,11 +77,17 @@ Loop:
 
 		buf, cur = display.RenderOver(buf, cur, front, back, display.Model24)
 		front, back = back, front
-		os.Stdout.Write(buf)
+		_, err = os.Stdout.Write(buf)
+		if err != nil {
+			return err
+		}
 		buf = buf[0:0]
 
 		var rbuf [1]byte
-		os.Stdin.Read(rbuf[0:1])
+		_, err = os.Stdin.Read(rbuf[0:1])
+		if err != nil {
+			return err
+		}
 
 		switch rbuf[0] {
 		case ' ':
@@ -101,7 +112,10 @@ Loop:
 	buf, cur = cur.Home(buf)
 	buf, cur = cur.Clear(buf)
 	buf, cur = cur.Show(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
+	if err != nil {
+		return err
+	}
 	buf = buf[0:0]
-	return nil
+	return err
 }
diff --git a/internal/cops/examples/brailleline/main.go b/internal/cops/examples/brailleline/main.go
index 06305ec..4d92ba7 100644
--- a/internal/cops/examples/brailleline/main.go
+++ b/internal/cops/examples/brailleline/main.go
@@ -12,12 +12,12 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 	w, h := 32, 16
 	pb := image.Rect(0, 0, w, h)
 	bb := braille.Bounds(pb)
@@ -38,7 +38,7 @@ func Main() error {
 	cur := display.Reset
 	buf, cur = display.Render(buf, cur, front, display.Model0)
 	buf = append(buf, "\r\n"...)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 
-	return nil
+	return err
 }
diff --git a/internal/cops/examples/braillematrix/main.go b/internal/cops/examples/braillematrix/main.go
index 3e3eedd..f37f19f 100644
--- a/internal/cops/examples/braillematrix/main.go
+++ b/internal/cops/examples/braillematrix/main.go
@@ -12,12 +12,12 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 
 	w, h := 16, 16
 	pb := image.Rect(0, 0, w, h)
@@ -66,7 +66,7 @@ func Main() error {
 	cur := display.Reset
 	buf, cur = display.Render(buf, cur, page, display.Model8)
 	buf = append(buf, "\r\n"...)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 
-	return nil
+	return err
 }
diff --git a/internal/cops/examples/braillewave/main.go b/internal/cops/examples/braillewave/main.go
index d316c79..0df0d9f 100644
--- a/internal/cops/examples/braillewave/main.go
+++ b/internal/cops/examples/braillewave/main.go
@@ -14,15 +14,20 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 	term := terminal.New(os.Stdout.Fd())
-	defer term.Restore()
-	term.SetRaw()
+	defer func() {
+		err = term.Restore()
+	}()
+	err = term.SetRaw()
+	if err != nil {
+		return err
+	}
 
 	bounds, err := term.Bounds()
 	if err != nil {
@@ -34,7 +39,7 @@ func Main() error {
 	stopper := make(chan struct{}, 0)
 	go func() {
 		var rbuf [1]byte
-		os.Stdin.Read(rbuf[0:1])
+		_, err = os.Stdin.Read(rbuf[0:1])
 		close(stopper)
 	}()
 
@@ -69,7 +74,10 @@ Loop:
 
 		buf, cur = display.RenderOver(buf, cur, front, back, display.Model24)
 		front, back = back, front
-		os.Stdout.Write(buf)
+		_, err = os.Stdout.Write(buf)
+		if err != nil {
+			return err
+		}
 		buf = buf[0:0]
 
 		select {
@@ -84,8 +92,8 @@ Loop:
 	buf, cur = cur.Home(buf)
 	buf, cur = cur.Clear(buf)
 	buf, cur = cur.Show(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 	buf = buf[0:0]
 
-	return nil
+	return err
 }
diff --git a/internal/cops/examples/earthgif/earthgif.go b/internal/cops/examples/earthgif/earthgif.go
index 73b2b9a..129dd76 100644
--- a/internal/cops/examples/earthgif/earthgif.go
+++ b/internal/cops/examples/earthgif/earthgif.go
@@ -15,15 +15,20 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 	term := terminal.New(os.Stdin.Fd())
-	defer term.Restore()
-	term.SetRaw()
+	defer func() {
+		err = term.Restore()
+	}()
+	err = term.SetRaw()
+	if err != nil {
+		return err
+	}
 
 	data, err := Asset("earth.gif")
 	if err != nil {
@@ -62,7 +67,10 @@ func Main() error {
 	go func() {
 		var rbuf [1]byte
 		for {
-			os.Stdin.Read(rbuf[0:1])
+			_, err := os.Stdin.Read(rbuf[0:1])
+			if err != nil {
+				break
+			}
 			keypress <- rbuf[0]
 		}
 	}()
@@ -78,7 +86,10 @@ Loop:
 		buf, cur = display.RenderOver(buf, cur, front, back, display.Model24)
 		front, back = back, front
 		buf, cur = cur.Home(buf)
-		os.Stdout.Write(buf)
+		_, err = os.Stdout.Write(buf)
+		if err != nil {
+			break Loop
+		}
 		buf = buf[0:0]
 
 		delay := time.Duration(imgs.Delay[i]) * time.Millisecond * 10
@@ -98,10 +109,10 @@ Loop:
 	buf, cur = cur.Home(buf)
 	buf, cur = cur.Clear(buf)
 	buf, cur = cur.Show(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 	buf = buf[0:0]
 
-	return nil
+	return err
 }
 
 func projectCenterPreserveAspect(inner, outer image.Point) image.Rectangle {
diff --git a/internal/cops/examples/hicops/hicops.go b/internal/cops/examples/hicops/hicops.go
index 6ac1c7d..0a337a4 100644
--- a/internal/cops/examples/hicops/hicops.go
+++ b/internal/cops/examples/hicops/hicops.go
@@ -14,15 +14,20 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 	term := terminal.New(os.Stdin.Fd())
-	defer term.Restore()
-	term.SetRaw()
+	defer func() {
+		err = term.Restore()
+	}()
+	err = term.SetRaw()
+	if err != nil {
+		return
+	}
 
 	bounds, err := term.Bounds()
 	if err != nil {
@@ -51,17 +56,23 @@ func Main() error {
 	buf, cur = cur.Home(buf)
 	buf, cur = display.Render(buf, cur, front, display.Model24)
 	buf, cur = cur.Home(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
+	if err != nil {
+		return err
+	}
 	buf = buf[0:0]
 
 	var input [1]byte
-	os.Stdin.Read(input[0:1])
+	_, err = os.Stdin.Read(input[0:1])
+	if err != nil {
+		return err
+	}
 
 	buf, cur = cur.Home(buf)
 	buf, cur = cur.Clear(buf)
 	buf, cur = cur.Show(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 	buf = buf[0:0]
 
-	return nil
+	return err
 }
diff --git a/internal/cops/examples/vt/main.go b/internal/cops/examples/vt/main.go
index bb7d58d..a1113e7 100644
--- a/internal/cops/examples/vt/main.go
+++ b/internal/cops/examples/vt/main.go
@@ -13,15 +13,20 @@ import (
 )
 
 func main() {
-	if err := Main(); err != nil {
+	if err := run(); err != nil {
 		fmt.Printf("%v\n", err)
 	}
 }
 
-func Main() error {
+func run() (err error) {
 	term := terminal.New(os.Stdin.Fd())
-	defer term.Restore()
-	term.SetRaw()
+	defer func() {
+		err = term.Restore()
+	}()
+	err = term.SetRaw()
+	if err != nil {
+		return err
+	}
 
 	leader, follower, err := termios.Pty()
 	if err != nil {
@@ -46,7 +51,9 @@ func Main() error {
 	}
 
 	vtw := vtio.NewDisplayWriter(bounds)
-	go io.Copy(vtw, leader)
+	go func() {
+		_, err = io.Copy(vtw, leader)
+	}()
 
 	front, back := display.New2(bounds)
 
@@ -61,7 +68,7 @@ func Main() error {
 	r := make(chan struct{}, 0)
 	go func() {
 		var rbuf [1]byte
-		os.Stdin.Read(rbuf[0:1])
+		_, err = os.Stdin.Read(rbuf[0:1])
 		close(r)
 	}()
 
@@ -73,7 +80,10 @@ DrawLoop:
 			buf, cur = display.RenderOver(buf, cur, front, back, display.Model24)
 			front, back = back, front
 			// fmt.Printf("%q\r\n", buf)
-			os.Stdout.Write(buf)
+			_, err = os.Stdout.Write(buf)
+			if err != nil {
+				break DrawLoop
+			}
 			buf = buf[0:0]
 		case <-r:
 			break DrawLoop
@@ -84,8 +94,8 @@ DrawLoop:
 	buf, cur = cur.Home(buf)
 	buf, cur = cur.Clear(buf)
 	buf, cur = cur.Show(buf)
-	os.Stdout.Write(buf)
+	_, err = os.Stdout.Write(buf)
 	buf = buf[0:0]
 
-	return nil
+	return err
 }
diff --git a/internal/cops/terminal/terminal.go b/internal/cops/terminal/terminal.go
index 99f5446..ce0c0cf 100644
--- a/internal/cops/terminal/terminal.go
+++ b/internal/cops/terminal/terminal.go
@@ -21,7 +21,7 @@ type Terminal struct {
 // that terminal to its current state.
 func New(fd uintptr) Terminal {
 	t := Terminal{fd: fd}
-	termios.Tcgetattr(fd, &t.old)
+	_ = termios.Tcgetattr(fd, &t.old)
 	t.now = t.old
 	return t
 }
diff --git a/internal/cops/vtio/vtio.go b/internal/cops/vtio/vtio.go
index 3b168cf..d36c019 100644
--- a/internal/cops/vtio/vtio.go
+++ b/internal/cops/vtio/vtio.go
@@ -1,3 +1,5 @@
+// Package vtio provides a tool for drawing a ANSI stream onto a virtualized
+// display.
 package vtio
 
 import (
@@ -12,6 +14,9 @@ import (
 	"github.com/borkshop/bork/internal/cops/display"
 )
 
+// NewDisplayWriter creates an IO writer into which you can write virtual
+// terminal codes (ANSI) and capture the resulting virtualized display state.
+// The implementation of the ANSI language is far from complete.
 func NewDisplayWriter(rect image.Rectangle) *DisplayWriter {
 	dis := display.New(rect)
 	handler := &displayWriterHandler{
@@ -27,15 +32,20 @@ func NewDisplayWriter(rect image.Rectangle) *DisplayWriter {
 	}
 }
 
+// DisplayWriter captures ANSI terminal commands and draws them onto a virtual
+// display.
 type DisplayWriter struct {
 	parser  *ansiterm.AnsiParser
 	handler *displayWriterHandler
 }
 
+// C returns a read channel. This channel will receive a non-blocking write
+// whenever the underlying display changes.
 func (d *DisplayWriter) C() <-chan struct{} {
 	return d.handler.c
 }
 
+// Write draws ANSI virtual terminal bytes onto the underlying virtual display.
 func (d *DisplayWriter) Write(buf []byte) (int, error) {
 	d.handler.lock.Lock()
 	defer d.handler.lock.Unlock()
@@ -50,12 +60,14 @@ func (d *DisplayWriter) Write(buf []byte) (int, error) {
 	return count, err
 }
 
+// Draw captures the current display state.
 func (d *DisplayWriter) Draw(e *display.Display, r image.Rectangle) {
 	d.handler.lock.RLock()
 	defer d.handler.lock.RUnlock()
 	display.Draw(e, r, d.handler.dis, image.ZP, draw.Src)
 }
 
+// Resize reallocates the display with different dimensions.
 func (d *DisplayWriter) Resize(rect image.Rectangle) {
 	d.handler.lock.Lock()
 	defer d.handler.lock.Unlock()
@@ -110,7 +122,9 @@ func (h *displayWriterHandler) Print(b byte) error {
 
 func (h *displayWriterHandler) Execute(b byte) error {
 	// fmt.Printf("E %q\r\n", string(b))
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	switch b {
 	case '\n':
 		h.pos.Y++
@@ -128,7 +142,9 @@ func (h *displayWriterHandler) Execute(b byte) error {
 
 // Cursor up
 func (h *displayWriterHandler) CUU(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CUU\n")
 	h.pos.Y -= i
 	// if h.pos.Y < h.dis.Rect.Min.Y {
@@ -139,7 +155,9 @@ func (h *displayWriterHandler) CUU(i int) error {
 
 // Cursor down
 func (h *displayWriterHandler) CUD(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CUD\n")
 	h.pos.Y += i
 	// if h.pos.Y >= h.dis.Rect.Max.Y {
@@ -150,7 +168,9 @@ func (h *displayWriterHandler) CUD(i int) error {
 
 // Cursor forward
 func (h *displayWriterHandler) CUF(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CUF\n")
 	h.pos.X += i
 	// if h.pos.X >= h.dis.Rect.Max.X {
@@ -161,7 +181,9 @@ func (h *displayWriterHandler) CUF(i int) error {
 
 // Cursor backward
 func (h *displayWriterHandler) CUB(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CUB\n")
 	h.pos.X -= i
 	// if h.pos.X < h.dis.Rect.Min.X {
@@ -172,19 +194,25 @@ func (h *displayWriterHandler) CUB(i int) error {
 
 // Cursor new line?
 func (h *displayWriterHandler) CNL(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CNL\n")
 	return nil
 }
 
 func (h *displayWriterHandler) CPL(int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	// fmt.Printf("CPL\n")
 	return nil
 }
 
 func (h *displayWriterHandler) CHA(i int) error {
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	h.pos.X = i - 1
 	return nil
 }
@@ -199,7 +227,9 @@ func (h *displayWriterHandler) VPA(i int) error {
 // Cursor update
 func (h *displayWriterHandler) CUP(y, x int) error {
 	// fmt.Printf("CUP\r\n")
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 	h.pos.X = x - 1
 	h.pos.Y = y - 1
 	return nil
@@ -207,8 +237,7 @@ func (h *displayWriterHandler) CUP(y, x int) error {
 
 // Horizontal vertical position
 func (h *displayWriterHandler) HVP(y, x int) error {
-	h.CUP(y, x)
-	return nil
+	return h.CUP(y, x)
 }
 
 // Text cursor enable mode (show or hide cursor)
@@ -230,8 +259,7 @@ func (h *displayWriterHandler) DECCOLM(bool) error {
 // Erase display
 func (h *displayWriterHandler) ED(i int) error {
 	// fmt.Printf("ED\r\n")
-	h.Flush()
-	return nil
+	return h.Flush()
 }
 
 // Erase line
@@ -275,7 +303,9 @@ func (h *displayWriterHandler) DCH(int) error {
 // Set graphics rendition
 func (h *displayWriterHandler) SGR(codes []int) error {
 	// fmt.Printf("SGR %#v\r\n", codes)
-	h.Flush()
+	if err := h.Flush(); err != nil {
+		return err
+	}
 
 	if len(codes) == 0 {
 		h.fg = display.Colors[7]
diff --git a/internal/hilbert/hilbert.go b/internal/hilbert/hilbert.go
index 326c453..39c0812 100644
--- a/internal/hilbert/hilbert.go
+++ b/internal/hilbert/hilbert.go
@@ -2,16 +2,24 @@ package hilbert
 
 import "image"
 
+// Scale is the width and height of a Hilbert space-filling curve.
+// The scale must be a power of two.
 type Scale int
 
+// Encode returns the linear index of a point along a Hilbert curve with this
+// scale.
 func (scale Scale) Encode(pt image.Point) int {
 	return Encode(pt, int(scale))
 }
 
+// Decode returns the point at the given offset of a Hilbert curve with this
+// scale.
 func (scale Scale) Decode(hi int) image.Point {
 	return Decode(hi, int(scale))
 }
 
+// Encode returns the linear index of a point along a Hilbert curve for a given
+// scale.
 func Encode(pt image.Point, scale int) int {
 	var rotation image.Point
 	h := 0
@@ -24,6 +32,8 @@ func Encode(pt image.Point, scale int) int {
 	return h
 }
 
+// Decode returns the point corresponding to a given position along a Hilbert
+// curve of particular size.
 func Decode(h int, scale int) image.Point {
 	var pt, rotation image.Point
 	for s := 1; s < scale; s <<= 1 {
diff --git a/internal/input/channel.go b/internal/input/channel.go
index 86b8320..4829ac0 100644
--- a/internal/input/channel.go
+++ b/internal/input/channel.go
@@ -1,3 +1,7 @@
+// Package input provides an adapter that changes a stream of terminal input
+// into a channel of commands.
+// To use the command channel, read command by command and switch on the
+// command type.
 package input
 
 import (
@@ -7,7 +11,10 @@ import (
 	"unicode"
 )
 
+// Move captures a motion command. The data are a unit vector.
 type Move image.Point
+
+// ShiftMove captures a motion command with the shift key pressed. The data are a unit vector.
 type ShiftMove image.Point
 
 // Channel returns a read channel for commands, distinguishable by type, and a
diff --git a/internal/perf/perf.go b/internal/perf/perf.go
index 6dcca56..fff27e3 100644
--- a/internal/perf/perf.go
+++ b/internal/perf/perf.go
@@ -143,7 +143,7 @@ func (perf *Perf) stopProfiling() (err error) {
 	}
 	perf.shouldProfile = false
 	perf.profiling = false
-	return nil
+	return err
 }
 
 func (perf *Perf) takeProfile() error {
diff --git a/proofs/showroom/main.go b/proofs/showroom/main.go
index 6e59d28..ce7907c 100644
--- a/proofs/showroom/main.go
+++ b/proofs/showroom/main.go
@@ -40,7 +40,7 @@ func run() (rerr error) {
 	commands, mute := input.Channel(os.Stdin)
 	defer mute()
 
-	sigwinch := make(chan os.Signal)
+	sigwinch := make(chan os.Signal, 1)
 	signal.Notify(sigwinch, syscall.SIGWINCH)
 
 	world := newWorld()
diff --git a/proofs/splash/main.go b/proofs/splash/main.go
index ca24036..e227c60 100644
--- a/proofs/splash/main.go
+++ b/proofs/splash/main.go
@@ -48,7 +48,7 @@ func run() (rerr error) {
 	commands, mute := input.Channel(os.Stdin)
 	defer mute()
 
-	sigwinch := make(chan os.Signal)
+	sigwinch := make(chan os.Signal, 1)
 	signal.Notify(sigwinch, syscall.SIGWINCH)
 
 	ticker := time.NewTicker(time.Second / 60)