Fix possible segfault in X backend

backends/x/event.go

@@ -33,6 +33,10 @@ func (backend *Backend) handleConfigureNotify (
 		configureEvent =
 			backend.compressConfigureNotify(configureEvent)
 
+		// we should not resize the canvas while drawing is taking place
+		backend.drawLock.Lock()
+		defer backend.drawLock.Unlock()
+
 		// resize buffer
 		width, height := backend.calculateBufferSize()
 		backend.application.SetSize(width, height)

examples/color/main.go

@@ -44,7 +44,7 @@ func main () {
 }
 
 func redraw () {
-	text :="RAINBOW :D"
+	text := "RAINBOW :D"
 	width, height := application.Size()
 	
 	application.Dot.X = (width - len(text)) / 2