Index: binaries/data/mods/mod/gui/common/guitags.js
===================================================================
--- binaries/data/mods/mod/gui/common/guitags.js
+++ binaries/data/mods/mod/gui/common/guitags.js
@@ -21,3 +21,8 @@
 
 	return result;
 }
+
+function iconTag(iconName)
+{
+	return '[icon="' + iconName + '"]';
+}
Index: source/gui/CGUI.h
===================================================================
--- source/gui/CGUI.h
+++ source/gui/CGUI.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -220,7 +220,6 @@
 	 */
 	SGUIText GenerateText(const CGUIString& Text, const CStrW& Font, const float& Width, const float& BufferZone, const IGUIObject* pObject = NULL);
 
-
 	/**
 	 * Check if an icon exists
 	 */
@@ -232,6 +231,12 @@
 	SGUIIcon GetIcon(const CStr& str) const { return m_Icons.find(str)->second; }
 
 	/**
+	 * Loads a new icon at runtime.
+	 * Returns false if an icon of that name exists and was not overwritten, true otherwise.
+	 */
+	bool AddIcon(const CStr& name, const CStr& sprite, const CStr& size, bool replaceExisting);
+
+	/**
 	 * Get pre-defined color (if it exists)
 	 * Returns false if it fails.
 	 */
Index: source/gui/CGUI.cpp
===================================================================
--- source/gui/CGUI.cpp
+++ source/gui/CGUI.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -1664,6 +1664,29 @@
 	m_ScrollBarStyles[name] = scrollbar;
 }
 
+bool CGUI::AddIcon(const CStr& name, const CStr& sprite, const CStr& size, bool replaceExisting)
+{
+	if (IconExists(name))
+	{
+		if (!replaceExisting)
+			return false;
+
+		m_Icons.erase(name);
+	}
+
+	CSize cSize;
+	if (!GUI<CSize>::ParseString(size.FromUTF8(), cSize))
+	{
+		LOGERROR("Error parsing '%s' (\"%s\") inside <icon>.", name, size);
+		return false;
+	}
+
+	m_Icons[name].m_Size = cSize;
+	m_Icons[name].m_SpriteName = sprite;
+
+	return true;
+}
+
 void CGUI::Xeromyces_ReadIcon(XMBElement Element, CXeromyces* pFile)
 {
 	SGUIIcon icon;
Index: source/gui/scripting/JSInterface_GUIManager.h
===================================================================
--- source/gui/scripting/JSInterface_GUIManager.h
+++ source/gui/scripting/JSInterface_GUIManager.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -32,6 +32,7 @@
 	void ResetCursor(ScriptInterface::CxPrivate* pCxPrivate);
 	bool TemplateExists(ScriptInterface::CxPrivate* pCxPrivate, const std::string& templateName);
 	CParamNode GetTemplate(ScriptInterface::CxPrivate* pCxPrivate, const std::string& templateName);
+	bool AddIcon(ScriptInterface::CxPrivate* pCxPrivate, const std::string& name, const std::string& sprite, const std::string& size, bool replaceExisting);
 
 	void RegisterScriptFunctions(const ScriptInterface& scriptInterface);
 }
Index: source/gui/scripting/JSInterface_GUIManager.cpp
===================================================================
--- source/gui/scripting/JSInterface_GUIManager.cpp
+++ source/gui/scripting/JSInterface_GUIManager.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -77,6 +77,12 @@
 	return g_GUI->GetTemplate(templateName);
 }
 
+bool JSI_GUIManager::AddIcon(ScriptInterface::CxPrivate* pCxPrivate, const std::string& name, const std::string& sprite, const std::string& size, bool replaceExisting)
+{
+	CGUI* guiPage = static_cast<CGUI*>(pCxPrivate->pCBData);
+	return guiPage->AddIcon(name, sprite, size, replaceExisting);
+}
+
 void JSI_GUIManager::RegisterScriptFunctions(const ScriptInterface& scriptInterface)
 {
 	scriptInterface.RegisterFunction<void, std::wstring, JS::HandleValue, &PushGuiPage>("PushGuiPage");
@@ -88,4 +94,5 @@
 	scriptInterface.RegisterFunction<void, &ResetCursor>("ResetCursor");
 	scriptInterface.RegisterFunction<bool, std::string, &TemplateExists>("TemplateExists");
 	scriptInterface.RegisterFunction<CParamNode, std::string, &GetTemplate>("GetTemplate");
+	scriptInterface.RegisterFunction<bool, std::string, std::string, std::string, bool, &AddIcon>("AddIcon");
 }