Index: binaries/data/mods/mod/gui/common/functions_msgbox.js
===================================================================
--- binaries/data/mods/mod/gui/common/functions_msgbox.js
+++ binaries/data/mods/mod/gui/common/functions_msgbox.js
@@ -15,6 +15,24 @@
 		});
 }
 
+function timedConfirmation(mbWidth, mbHeight, mbMessage, mbTimeout, mbTitle, mbButtonCaptions, mbBtnCode, mbCallbackArgs)
+{
+	Engine.PushGuiPage(
+		"page_timedconfirmation.xml",
+		{
+			"width": mbWidth,
+			"height": mbHeight,
+			"message": mbMessage,
+			"timeout": mbTimeout,
+			"title": mbTitle,
+			"buttonCaptions": mbButtonCaptions
+		},
+		btnCode => {
+			if (mbBtnCode !== undefined && mbBtnCode[btnCode])
+				mbBtnCode[btnCode](mbCallbackArgs ? mbCallbackArgs[btnCode] : undefined);
+		});
+}
+
 function openURL(url)
 {
 	Engine.OpenURL(url);
Index: binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js
===================================================================
--- /dev/null
+++ binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js
@@ -0,0 +1,83 @@
+/**
+ * Currently limited to at most 3 buttons per message box.
+ * The convention is to have "cancel" appear first.
+ */
+function init(data)
+{
+	// Set title
+	Engine.GetGUIObjectByName("mbTitleBar").caption = data.title;
+
+	// Set subject
+	let mbTextObj = Engine.GetGUIObjectByName("mbText");
+	let mbTimerObj = Engine.GetGUIObjectByName("mbTimer");
+	mbTextObj.caption = data.message;
+
+	updateDisplayedTimer(data.timeout);
+
+	mbTimerObj.caption = data.timeout;
+	if (data.font) {
+		mbTextObj.font = data.font;
+	}
+
+	// Default behaviour
+	let mbCancelHotkey = Engine.GetGUIObjectByName("mbCancelHotkey");
+	mbCancelHotkey.onPress = Engine.PopGuiPage;
+
+	// Calculate size
+	let mbLRDiff = data.width / 2;
+	let mbUDDiff = data.height / 2;
+	Engine.GetGUIObjectByName("mbMain").size = "50%-" + mbLRDiff + " 50%-" + mbUDDiff + " 50%+" + mbLRDiff + " 50%+" + mbUDDiff;
+
+	let captions = data.buttonCaptions || [translate("OK")];
+
+	// Set button captions and visibility
+	let mbButton = [];
+	captions.forEach((caption, i) => {
+		mbButton[i] = Engine.GetGUIObjectByName("mbButton" + (i + 1));
+		mbButton[i].caption = caption;
+		mbButton[i].hidden = false;
+		mbButton[i].onPress = () => {
+			Engine.PopGuiPage(i);
+		};
+
+		// Convention: Cancel is the first button
+		if (i == 0)
+			mbCancelHotkey.onPress = mbButton[i].onPress;
+	});
+
+	// Distribute buttons horizontally
+	let y1 = "100%-46";
+	let y2 = "100%-18";
+	switch (captions.length)
+	{
+	case 1:
+		mbButton[0].size = "18 " + y1 + " 100%-18 " + y2;
+		break;
+	case 2:
+		mbButton[0].size = "18 " + y1 + " 50%-5 " + y2;
+		mbButton[1].size = "50%+5 " + y1 + " 100%-18 " + y2;
+		break;
+	case 3:
+		mbButton[0].size = "18 " + y1 + " 33%-5 " + y2;
+		mbButton[1].size = "33%+5 " + y1 + " 66%-5 " + y2;
+		mbButton[2].size = "66%+5 " + y1 + " 100%-18 " + y2;
+		break;
+	}
+}
+
+function onTick() {
+	let mbTimerObj = Engine.GetGUIObjectByName("mbTimer");
+	let time = +mbTimerObj.caption;
+	--time;
+	if (time < 1) {
+		let action = Engine.GetGUIObjectByName("mbButton1");
+		action.onPress();
+	}
+	mbTimerObj.caption = time;
+	updateDisplayedTimer(time);
+}
+
+function updateDisplayedTimer(time) {
+	let mbTimerDisplayObj = Engine.GetGUIObjectByName("mbTimerDisplay");
+	mbTimerDisplayObj.caption = Math.ceil(time/100);
+}
Index: binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml
===================================================================
--- /dev/null
+++ binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<objects>
+
+	<script directory="gui/common/"/>
+	<script directory="gui/timedconfirmation/"/>
+
+	<!-- Fade out the background because it's non-interactable -->
+	<object sprite="ModernFade" type="image"/>
+	<object name="mbCancelHotkey" hotkey="cancel" />
+	<object name="mbMain"
+			style="ModernDialog"
+			type="image"
+	>
+		<action on="Tick">
+			onTick();
+		</action>
+	<object name="mbTitleBar"
+			style="ModernLabelText"
+			type="text"
+			size="50%-128 -18 50%+128 14"
+	/>
+	<object name="mbTimerDisplay"
+			type="text"
+			style="ModernLabelText"
+			size="18 28 100%-18 38"
+	/>
+	<object name="mbText"
+			type="text"
+			style="ModernLabelText"
+			size="18 40 100%-18 100%-64"
+	/>
+	<object name="mbTimer"
+			type="text"
+			style="ModernLabelText"
+			size="18 18 100%-18 100%-64"
+			hidden="true"
+	/>
+	<!-- The size of the following buttons is set dynamically in timedconfirmation.js -->
+	<object name="mbButton1"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	<object name="mbButton2"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	<object name="mbButton3"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	</object>
+</objects>
Index: binaries/data/mods/public/gui/options/options.js
===================================================================
--- binaries/data/mods/public/gui/options/options.js
+++ binaries/data/mods/public/gui/options/options.js
@@ -146,6 +146,35 @@
 			};
 		}
 	},
+	"dropdownNumber":
+	{
+		"configToValue": value => +value,
+		"valueToGui": (value, control) => {
+			control.selected = control.list_data.indexOf(""+value);
+		},
+		"guiToValue": control => +control.list_data[control.selected],
+		"guiSetter": "onSelectionChange",
+		"initGUI": (option, control) => {
+			control.list = option.list.map(e => e.label);
+			control.list_data = option.list.map(e => e.value);
+			control.onHoverChange = () => {
+				let item = option.list[control.hovered];
+				control.tooltip = item && item.tooltip || option.tooltip;
+			};
+		},
+		"timeout": (option, oldValue, hasChanges, newValue) => {
+			if (!option.timeout)
+				return;
+			timedConfirmation(
+				500, 200,
+				translate("Do you want to keep changes?"),
+				500,
+				translate("Warning"),
+				[translate("No"), translate("Yes")],
+				[() => {this.revertChange(option, +oldValue, hasChanges);}, null]
+			);
+		}
+	},
 	"slider":
 	{
 		"configToValue": value => +value,
@@ -242,14 +271,20 @@
 			if (optionType.sanitizeValue)
 				optionType.sanitizeValue(value, control, option);
 
+			let oldValue = optionType.configToValue(Engine.ConfigDB_GetValue("user", option.config));
+			
 			control.tooltip = option.tooltip + (optionType.tooltip ? "\n" + optionType.tooltip(value, option) : "");
 
+			let hasChanges = Engine.ConfigDB_HasChanges("user");
 			Engine.ConfigDB_CreateValue("user", option.config, String(value));
 			Engine.ConfigDB_SetChanges("user", true);
 
 			g_ChangedKeys.add(option.config);
 			fireConfigChangeHandlers(new Set([option.config]));
 
+			if (option.timeout)
+				optionType.timeout(option, oldValue, hasChanges, value);
+
 			if (option.function)
 				Engine[option.function](value);
 
@@ -315,6 +350,18 @@
 	revertChanges();
 }
 
+function revertChange(option, oldValue, hadChanges)
+{
+	if (!hadChanges)
+		Engine.ConfigDB_SetChanges("user", false);
+
+	Engine.ConfigDB_CreateValue("user", option.config, String(oldValue));
+	if (option.function)
+		Engine[option.function](oldValue);
+
+	displayOptions();
+}
+
 function revertChanges()
 {
 	Engine.ConfigDB_Reload("user");
Index: binaries/data/mods/public/gui/options/options.json
===================================================================
--- binaries/data/mods/public/gui/options/options.json
+++ binaries/data/mods/public/gui/options/options.json
@@ -149,6 +149,23 @@
 				"config": "adaptivefps.session",
 				"min": 20,
 				"max": 100
+			},
+			{
+				"type": "dropdownNumber",
+				"label": "GUI scale",
+				"timeout": 500,
+				"tooltip": "GUI scale",
+				"config": "gui.scale",
+				"function": "SetGUIScale",
+				"list": [
+					{ "value": 0.75, "label": "75%" },
+					{ "value": 1.00, "label": "100%" },
+					{ "value": 1.25, "label": "125%" },
+					{ "value": 1.75, "label": "175%" },
+					{ "value": 2.00, "label": "200%" },
+					{ "value": 2.25, "label": "225%" },
+					{ "value": 2.50, "label": "250%" }
+				]
 			}
 		]
 	},
Index: binaries/data/mods/public/gui/options/options.xml
===================================================================
--- binaries/data/mods/public/gui/options/options.xml
+++ binaries/data/mods/public/gui/options/options.xml
@@ -33,6 +33,7 @@
 					</object>
 					<object name="option_control_number[n]" size="65% 0 100%-8 100%" type="input" style="ModernInput"/>
 					<object name="option_control_dropdown[n]" size="65% 0 100%-8 100%" type="dropdown" style="ModernDropDown" tooltip_style="tooltipInstant"/>
+					<object name="option_control_dropdownNumber[n]" size="65% 0 100%-8 100%" type="dropdown" style="ModernDropDown" tooltip_style="tooltipInstant"/>
 					<object name="option_control_slider[n]" size="65% 0 100%-8 100%" type="slider" style="ModernSlider"/>
 				</object>
 			</repeat>
Index: source/ps/GameSetup/Config.cpp
===================================================================
--- source/ps/GameSetup/Config.cpp
+++ source/ps/GameSetup/Config.cpp
@@ -51,7 +51,6 @@
 	CFG_GET_VAL("gui.scale", g_GuiScale);
 }
 
-
 static void ProcessCommandLineArgs(const CmdLineArgs& args)
 {
 	// TODO: all these options (and the ones processed elsewhere) should
Index: source/ps/VideoMode.h
===================================================================
--- source/ps/VideoMode.h
+++ source/ps/VideoMode.h
@@ -47,6 +47,11 @@
 	bool ResizeWindow(int w, int h);
 
 	/**
+	 * Tell dependent compoenent to recompute sizes because scaling have changed.
+	 */
+	void Rescale();
+
+	/**
 	 * Switch to fullscreen or windowed mode.
 	 */
 	bool SetFullscreen(bool fullscreen);
Index: source/ps/VideoMode.cpp
===================================================================
--- source/ps/VideoMode.cpp
+++ source/ps/VideoMode.cpp
@@ -359,6 +359,12 @@
 	return true;
 }
 
+void CVideoMode::Rescale()
+{
+	ENSURE(m_IsInitialised);
+	UpdateRenderer(m_CurrentW, m_CurrentH);
+}
+
 bool CVideoMode::SetFullscreen(bool fullscreen)
 {
 	// This might get called before initialisation by psDisplayError;
Index: source/ps/scripting/JSInterface_ConfigDB.cpp
===================================================================
--- source/ps/scripting/JSInterface_ConfigDB.cpp
+++ source/ps/scripting/JSInterface_ConfigDB.cpp
@@ -24,9 +24,12 @@
 #include "scriptinterface/FunctionWrapper.h"
 #include "scriptinterface/ScriptRequest.h"
 
+#include "ps/VideoMode.h"
+
 #include <string>
 #include <unordered_set>
 
+extern float g_GuiScale;
 namespace JSI_ConfigDB
 {
 // These entries will not be readable nor writable for JS, so that e.g. malicious mods can't leak personal or sensitive data
@@ -188,6 +191,12 @@
 	return true;
 }
 
+void SetGUIScale(float scale)
+{
+	g_GuiScale = scale;
+	g_VideoMode.Rescale();
+}
+
 void RegisterScriptFunctions(const ScriptRequest& rq)
 {
 	ScriptFunction::Register<&HasChanges>(rq, "ConfigDB_HasChanges");
@@ -201,5 +210,6 @@
 	ScriptFunction::Register<&CreateAndWriteValueToFile>(rq, "ConfigDB_CreateAndWriteValueToFile");
 	ScriptFunction::Register<&SetFile>(rq, "ConfigDB_SetFile");
 	ScriptFunction::Register<&Reload>(rq, "ConfigDB_Reload");
+	ScriptFunction::Register<&SetGUIScale>(rq, "SetGUIScale");
 }
 }