resume with a new goroutine instead of busy wait

Related #461

ui.go

@@ -520,15 +520,20 @@ func newUI(screen tcell.Screen) *ui {
 		icons:     parseIcons(),
 	}
 
-	go func() {
+	go ui.pollEvents()
+
+	return ui
+}
+
+func (ui *ui) pollEvents() {
 	var ev tcell.Event
 	for {
 		ev = ui.screen.PollEvent()
+		if ev == nil {
+			return
+		}
 		ui.evChan <- ev
 	}
-	}()
-
-	return ui
 }
 
 func (ui *ui) renew() {
@@ -1058,6 +1063,8 @@ func (ui *ui) resume() {
 
 	ui.screen = screen
 
+	go ui.pollEvents()
+
 	ui.renew()
 }