Added tab completion to in-game chat.

Both player names and chat commands can be completed.
Names of local players and bots are not candidates for completion.
If a completed name is the first word ": " is appended to the end.
The hotkey for toggling team/all chat has been moved to left Alt.

OpenRA.Game/Widgets/TextFieldWidget.cs

@@ -30,6 +30,7 @@ namespace OpenRA.Widgets
 		public Func<bool> OnEnterKey = () => false;
 		public Func<bool> OnTabKey = () => false;
 		public Func<bool> OnEscKey = () => false;
+		public Func<bool> OnAltKey = () => false;
 		public Action OnLoseFocus = () => { };
 		public Action OnTextEdited = () => { };
 		public int CursorPosition { get; set; }
@@ -121,6 +122,9 @@ namespace OpenRA.Widgets
 			if (e.Key == Keycode.ESCAPE && OnEscKey())
 				return true;
 
+			if (e.Key == Keycode.LALT && OnAltKey())
+				return true;
+
 			if (e.Key == Keycode.LEFT)
 			{
 				if (CursorPosition > 0)

OpenRA.Mods.RA/Widgets/Logic/IngameChatLogic.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
@@ -30,6 +31,9 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 
 		readonly List<INotifyChat> chatTraits;
 
+		readonly List<string> commandNames;
+		readonly List<string> playerNames;
+
 		bool teamChat;
 
 		[ObjectCreator.UseCtor]
@@ -43,6 +47,9 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 			var disableTeamChat = world.LocalPlayer == null || world.LobbyInfo.IsSinglePlayer || !players.Any(p => p.IsAlliedWith(world.LocalPlayer));
 			teamChat = !disableTeamChat;
 
+			commandNames = chatTraits.OfType<ChatCommands>().SelectMany(x => x.Commands.Keys).Select(x => "/" + x).ToList();
+			playerNames = players.Select(x => x.PlayerName).ToList();
+
 			var chatPanel = (ContainerWidget)widget;
 			chatOverlay = chatPanel.Get<ContainerWidget>("CHAT_OVERLAY");
 			chatOverlayDisplay = chatOverlay.Get<ChatDisplayWidget>("CHAT_DISPLAY");
@@ -57,7 +64,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 			chatMode.IsDisabled = () => disableTeamChat;
 
 			chatText = chatChrome.Get<TextFieldWidget>("CHAT_TEXTFIELD");
-			chatText.OnTabKey = () =>
+			chatText.OnAltKey = () =>
 			{
 				if (!disableTeamChat)
 					teamChat ^= true;
@@ -76,6 +83,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 				CloseChat();
 				return true;
 			};
+			chatText.OnTabKey = () => AutoCompleteText();
 
 			chatText.OnEscKey = () => { CloseChat(); return true; };
 
@@ -166,5 +174,48 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 
 			Sound.PlayNotification(modRules, null, "Sounds", "ChatLine", null);
 		}
+
+		bool AutoCompleteText()
+		{
+			if (string.IsNullOrEmpty(chatText.Text))
+				return false;
+
+			string suggestion;
+
+			if (chatText.Text.StartsWith("/"))
+			{
+				suggestion = commandNames.FirstOrDefault(x => x.StartsWith(chatText.Text));
+				if (suggestion == null)
+					return false;
+			}
+			else
+			{
+				string toComplete;
+				bool oneWord;
+				if (chatText.Text.Contains(' '))
+				{
+					toComplete = chatText.Text.Substring(chatText.Text.LastIndexOf(' ') + 1);
+					oneWord = false;
+				}
+				else
+				{
+					toComplete = chatText.Text;
+					oneWord = true;
+				}
+
+				suggestion = playerNames.FirstOrDefault(x => x.StartsWith(toComplete, StringComparison.InvariantCultureIgnoreCase));
+				if (suggestion == null)
+					return false;
+
+				if (oneWord)
+					suggestion += ": ";
+				else
+					suggestion = chatText.Text.Substring(0, chatText.Text.Length - toComplete.Length) + suggestion;
+			}
+
+			chatText.Text = suggestion;
+			chatText.CursorPosition = chatText.Text.Length;
+			return true;
+		}
 	}
 }