From e233ea291cc6c3e6aabc09bde851f9e2abcaa1f2 Mon Sep 17 00:00:00 2001
From: Kyzentun Keeslala <kyzentun@gmail.com>
Date: Fri, 2 Feb 2018 11:15:34 -0700
Subject: [PATCH 1/2] Change ThemePrefs to use the Theme preference instead of
 GetThemeDisplayName or themeInfo because GetThemeDisplayName does not work
 when a theme falls back on another theme.

---
 Themes/_fallback/Scripts/02 ThemePrefs.lua | 34 +++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/Themes/_fallback/Scripts/02 ThemePrefs.lua b/Themes/_fallback/Scripts/02 ThemePrefs.lua
index 3efbfe94bd..55bb07791c 100644
--- a/Themes/_fallback/Scripts/02 ThemePrefs.lua	
+++ b/Themes/_fallback/Scripts/02 ThemePrefs.lua	
@@ -32,7 +32,29 @@ local PrefsTable = nil;
 -- Gets the name of the current theme using themeInfo
 -- if available and the ThemeManager name otherwise.
 local function GetThemeName()
-	return themeInfo and themeInfo.Name or THEME:GetThemeDisplayName()
+	-- When loading a fallback theme, the theme manager pretends that the theme
+	-- being loaded is the current theme.  THEME:GetCurThemeName and everything
+	-- else that relies on the current theme will think that the fallback theme
+	-- is the current theme.
+	-- This includes the themeInfo table that some themes create in
+	-- "00 ThemeInfo.lua".
+
+	-- In diagram form, imagine the "home" theme, which falls back on
+	-- "default", which falls back on "_fallback".
+	-- Scripts being loaded  |  Current theme name.  |  themeInfo source
+	-- -----------------------------------------------------------------
+	-- _fallback/Scripts     |  _fallback            |  _fallback/Scripts/
+	-- default/Scripts       |  default              |  default/Scripts/
+	-- home/Scripts          |  home                 |  home/Scripts/
+
+	-- So when default calls ThemePrefs.Init at the end of its script loading,
+	-- ThemePrefs thinks the current theme is "default", even if the player
+	-- chose "home".  Thus, the ThemePrefs entry for "home" is not created.
+	-- Then later when a preference is used, ResolveTable thinks the current
+	-- theme is "home", but fails because there is no "home" entry in
+	-- PrefsTable.
+
+	return PREFSMAN:GetPreference("Theme")
 end
 
 -- Given a preference name, returns the table it's in. Checks the current
@@ -149,6 +171,16 @@ ThemePrefs =
 		end
 		Warn( "Set: "..GetString("UnknownPreference"):format(name) )
 	end,
+
+	CopyPrefsFrom = function(name)
+		local curr_prefs = PrefsTable[GetThemeName()]
+		local from_prefs = PrefsTable[name]
+		if curr_prefs and from_prefs then
+			for pref_name, pref_value in pairs(from_prefs) do
+				curr_prefs[pref_name] = pref_value
+			end
+		end
+	end,
 };
 
 -- global aliases

From 02dd2522e37667e88ea4e24bef5f109f87c21575 Mon Sep 17 00:00:00 2001
From: Kyzentun Keeslala <kyzentun@gmail.com>
Date: Mon, 5 Feb 2018 09:12:35 -0700
Subject: [PATCH 2/2] Add THEME:get_theme_fallback_list function.

---
 src/ThemeManager.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/ThemeManager.cpp b/src/ThemeManager.cpp
index 97f4723f9a..17f2054775 100644
--- a/src/ThemeManager.cpp
+++ b/src/ThemeManager.cpp
@@ -1446,6 +1446,18 @@ public:
 		return 0;
 	}
 
+	static int get_theme_fallback_list(T* p, lua_State* L)
+	{
+		lua_createtable(L, g_vThemes.size(), 0);
+		int ret= lua_gettop(L);
+		for(size_t tid= 0; tid < g_vThemes.size(); ++tid)
+		{
+			lua_pushstring(L, g_vThemes[tid].sThemeName.c_str());
+			lua_rawseti(L, ret, tid+1);
+		}
+		return 1;
+	}
+
 	LunaThemeManager()
 	{
 		ADD_METHOD( ReloadMetrics );
@@ -1473,6 +1485,7 @@ public:
 		ADD_METHOD( GetMetricNamesInGroup );
 		ADD_METHOD( GetStringNamesInGroup );
 		ADD_METHOD( SetTheme );
+		ADD_METHOD(get_theme_fallback_list);
 	}
 };