xW: make Up/Down go through input history

The input field isn't multiline, so this doesn't pose an issue.
Otherwise, we'd have to check if we're on the top line first.

xW/xW.cpp

@@ -848,7 +848,7 @@ relay_process_message(const Relay::EventMessage &m)
 	{
 		auto pong = new Relay::CommandData_PingResponse();
 		pong->event_seq = m.event_seq;
-		relay_send(pong);
+		relay_send_now(pong);
 		break;
 	}
 
@@ -1301,6 +1301,32 @@ input_complete()
 	return true;
 }
 
+static bool
+input_up()
+{
+	auto b = buffer_by_name(g.buffer_current);
+	if (!b || b->history_at < 1)
+		return false;
+
+	if (b->history_at == b->history.size())
+		b->input = window_get_text(g.hwndInput);
+	input_set_contents(b->history.at(--b->history_at));
+	return true;
+}
+
+static bool
+input_down()
+{
+	auto b = buffer_by_name(g.buffer_current);
+	if (!b || b->history_at >= b->history.size())
+		return false;
+
+	input_set_contents(++b->history_at == b->history.size()
+		? b->input
+		: b->history.at(b->history_at));
+	return true;
+}
+
 static boolean
 input_wants(const MSG *message)
 {
@@ -1332,34 +1358,18 @@ input_proc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
 		return lResult;
 	}
 	case WM_SYSCHAR:
-	{
-		auto b = buffer_by_name(g.buffer_current);
-		if (!b)
-			break;
-
 		// TODO(p): Emacs-style cursor movement shortcuts.
 		switch (wParam) {
 		case 'p':
-		{
+			if (input_up())
-			if (b->history_at < 1)
+				return 0;
-				break;
+			break;
-			if (b->history_at == b->history.size())
-				b->input = window_get_text(g.hwndInput);
-			input_set_contents(b->history.at(--b->history_at));
-			return 0;
-		}
 		case 'n':
-		{
+			if (input_down())
-			if (b->history_at >= b->history.size())
+				return 0;
-				break;
+			break;
-			input_set_contents(++b->history_at == b->history.size()
-				? b->input
-				: b->history.at(b->history_at));
-			return 0;
-		}
 		}
 		break;
-	}
 	case WM_KEYDOWN:
 	{
 		HWND scrollable = IsWindowVisible(g.hwndBufferLog)
@@ -1367,6 +1377,14 @@ input_proc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam,
 			: g.hwndBuffer;
 
 		switch (wParam) {
+		case VK_UP:
+			if (input_up())
+				return 0;
+			break;
+		case VK_DOWN:
+			if (input_down())
+				return 0;
+			break;
 		case VK_PRIOR:
 			SendMessage(scrollable, EM_SCROLL, SB_PAGEUP, 0);
 			return 0;