diff --git a/gui/twmsg.cpp b/gui/twmsg.cpp
new file mode 100644
index 0000000..00c6931
--- /dev/null
+++ b/gui/twmsg.cpp
@@ -0,0 +1,129 @@
+/*
+	Copyright 2015 _that/TeamWin
+	This file is part of TWRP/TeamWin Recovery Project.
+
+	TWRP is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	TWRP is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with TWRP.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "../data.hpp"
+#include "pages.hpp"
+#include "resources.hpp"
+
+#include "twmsg.h"
+
+std::string Message::GetFormatString(const std::string& name) const
+{
+	std::string resname;
+	size_t pos = name.find('=');
+	if (pos == std::string::npos)
+		resname = name;
+	else
+		resname = name.substr(0, pos);
+
+	std::string formatstr = resourceLookup(resname);
+	bool notfound = formatstr.empty() || formatstr[0] == '[';  // HACK: TODO: integrate this with resource-not-found logic
+	if (notfound && pos != std::string::npos)
+		// resource not found - use the default format string specified after "="
+		formatstr = name.substr(pos + 1);
+	return formatstr;
+}
+
+// Look up in local replacement vars first, if not found then use outer lookup object
+class LocalLookup : public StringLookup
+{
+	const std::vector<std::string>& vars;
+	const StringLookup& next;
+	public:
+	LocalLookup(const std::vector<std::string>& vars, const StringLookup& next) : vars(vars), next(next) {}
+	virtual std::string operator()(const std::string& name) const
+	{
+		if (!name.empty() && isdigit(name[0])) { // {1}..{9}
+			int i = atoi(name.c_str());
+			if (i > 0 && i <= (int)vars.size())
+				return vars[i - 1];
+		}
+		return next(name);
+	}
+};
+
+// conversion to final string
+Message::operator std::string() const
+{
+	// do resource lookup
+	std::string str = GetFormatString(name);
+
+	LocalLookup lookup(variables, varLookup);
+
+	// now insert stuff into curly braces
+
+	size_t pos = 0;
+	while ((pos = str.find('{', pos)) < std::string::npos) {
+		size_t end = str.find('}', pos);
+		if (end == std::string::npos)
+			break;
+
+		std::string varname = str.substr(pos + 1, end - pos - 1);
+		std::string vartext = lookup(varname);
+
+		str.replace(pos, end - pos + 1, vartext);
+	}
+	// TODO: complain about too many or too few numbered replacement variables
+	return str;
+}
+
+/*
+Resource manager lookup
+*/
+class ResourceLookup : public StringLookup
+{
+public:
+	virtual std::string operator()(const std::string& name) const
+	{
+		const ResourceManager* res = PageManager::GetResources();
+		if (res)
+			return res->FindString(name);
+		return name;
+	}
+};
+ResourceLookup resourceLookup;
+
+
+/*
+DataManager lookup
+*/
+class DataLookup : public StringLookup
+{
+public:
+	virtual std::string operator()(const std::string& name) const
+	{
+		std::string value;
+		if (DataManager::GetValue(name, value) == 0)
+			return value;
+		else
+			return "";
+	}
+};
+DataLookup dataLookup;
+
+
+// Utility functions to create messages. Short names to make usage convenient.
+Message Msg(const char* name)
+{
+	return Message(msg::kNormal, name, resourceLookup, dataLookup);
+}
+
+Message Msg(msg::Kind kind, const char* name)
+{
+	return Message(kind, name, resourceLookup, dataLookup);
+}