Implement an auto-scroll setting for GUI lists.

Patch By: fpre / ffffffff
Fixes #4987, refs #4254

This allows the replay menu and lobby to focus the selected element if,
but only if it is expected by the user.
Replaces 3f5648767d which scrolled the selected player into view every
single time a new playerlist was received by the lobby server.

This was SVN commit r20958.

binaries/data/mods/mod/gui/gui.rnc

@@ -47,6 +47,7 @@ base_settings =
 # Defaults are not put in here, because it ruins the concept of styles.
 ex_settings =
   attribute anchor { valign }?&
+  attribute auto_scroll { bool }?&
   attribute buffer_zone { xsd:decimal }?&
   attribute buffer_width { xsd:decimal }?&
   attribute button_width { xsd:decimal }?&

binaries/data/mods/mod/gui/gui.rng

@@ -174,6 +174,11 @@
           <ref name="valign"/>
         </attribute>
       </optional>
+      <optional>
+        <attribute name="auto_scroll">
+          <ref name="bool"/>
+        </attribute>
+      </optional>
       <optional>
         <attribute name="buffer_zone">
           <data type="decimal"/>

binaries/data/mods/mod/gui/modmod/modmod.xml

@@ -62,6 +62,7 @@
 				selected_column_order="1"
 				size="0 25 100%-2 100%"
 				font="sans-stroke-13"
+				auto_scroll="true"
 			>
 				<action on="SelectionChange">showModDescription(this.name);</action>
 				<action on="SelectionColumnChange">applyFilters();</action>
@@ -113,6 +114,7 @@
 				size="0 25 96%-5 100%"
 				font="sans-stroke-13"
 				tooltip_style="pgToolTip"
+				auto_scroll="true"
 			>
 				<action on="SelectionChange">showModDescription(this.name);</action>
 				<action on="MouseLeftDoubleClickItem">disableMod();</action>

binaries/data/mods/public/gui/loadgame/load.xml

@@ -22,6 +22,7 @@
 				sortable="true"
 				size="24 4 100%-24 100%-70"
 				type="olist"
+				auto_scroll="true"
 			>
 				<action on="SelectionChange">selectionChanged();</action>
 				<action on="SelectionColumnChange">init();</action>

binaries/data/mods/public/gui/lobby/lobby.js

@@ -801,6 +801,7 @@ function selectGameFromPlayername()
 			if (g_SelectedPlayer != splitRatingFromNick(player.Name).nick)
 				continue;
 
+			gameList.auto_scroll = true;
 			if (player.Team == "observer")
 			{
 				foundAsObserver = true;
@@ -1084,6 +1085,8 @@ function updateGameList()
 	// Change these last, otherwise crash
 	gamesBox.list = list;
 	gamesBox.list_data = list_data;
+
+	gamesBox.auto_scroll = false;
 	gamesBox.selected = selectedGameIndex;
 
 	updateGameSelection();

binaries/data/mods/public/gui/replaymenu/replay_menu.xml

@@ -57,6 +57,7 @@
 				selected_column="months"
 				selected_column_order="-1"
 				font="sans-stroke-13"
+				auto_scroll="true"
 			>
 
 				<action on="SelectionChange">displayReplayDetails();</action>

source/gui/CList.cpp

@@ -45,6 +45,7 @@ CList::CList()
 	AddSetting(GUIST_CColor,				"textcolor");
 	AddSetting(GUIST_CColor,				"textcolor_selected");
 	AddSetting(GUIST_int,					"selected");	// Index selected. -1 is none.
+	AddSetting(GUIST_bool,					"auto_scroll");
 	AddSetting(GUIST_int,					"hovered");
 	AddSetting(GUIST_CStrW,					"tooltip");
 	AddSetting(GUIST_CStr,					"tooltip_style");
@@ -56,6 +57,7 @@ CList::CList()
 	GUI<bool>::SetSetting(this, "scrollbar", false);
 	GUI<int>::SetSetting(this, "selected", -1);
 	GUI<int>::SetSetting(this, "hovered", -1);
+	GUI<int>::SetSetting(this, "auto_scroll", false);
 
 	// Add scroll-bar
 	CGUIScrollBarVertical* bar = new CGUIScrollBarVertical();
@@ -161,6 +163,11 @@ void CList::HandleMessage(SGUIMessage& Message)
 		{
 			// TODO: Check range
 
+			bool auto_scroll;
+
+			GUI<bool>::GetSetting(this, "auto_scroll", auto_scroll);
+
+			if (auto_scroll)
 				UpdateAutoScroll();
 
 			// TODO only works if lower-case, shouldn't it be made case sensitive instead?