diff --git a/desktop/desktop.cpp b/desktop/desktop.cpp
index fb597e2..9ba9cc3 100644
--- a/desktop/desktop.cpp
+++ b/desktop/desktop.cpp
@@ -208,6 +208,7 @@ void EmbeddedWindowDestroyed(EsObjectID id);
 void ConfigurationWriteToFile();
 void OpenDocumentOpenReference(EsObjectID id);
 void OpenDocumentCloseReference(EsObjectID id);
+void WallpaperLoad(EsGeneric);
 
 #include "settings.cpp"
 
@@ -1901,6 +1902,7 @@ void DesktopSetup() {
 
 		EsWindow *window = desktop.setupDesktopUIComplete ? desktop.taskBar.window : EsWindowCreate(nullptr, ES_WINDOW_PLAIN);
 		window->messageUser = TaskBarWindowMessage;
+		window->appearActivated = true;
 		window->StartAnimating();
 		EsSyscall(ES_SYSCALL_WINDOW_SET_PROPERTY, window->handle, ES_WINDOW_SOLID_TRUE | ES_WINDOW_SOLID_NO_ACTIVATE, 0, ES_WINDOW_PROPERTY_SOLID);
 		EsSyscall(ES_SYSCALL_WINDOW_SET_PROPERTY, window->handle, BLEND_WINDOW_MATERIAL_GLASS, 0, ES_WINDOW_PROPERTY_MATERIAL);
diff --git a/desktop/gui.cpp b/desktop/gui.cpp
index 2fd3470..b95c70f 100644
--- a/desktop/gui.cpp
+++ b/desktop/gui.cpp
@@ -425,7 +425,7 @@ struct EsWindow : EsElement {
 
 	bool willUpdate, toolbarFillMode, destroyInstanceAfterClose, hasDialog, doNotPaint;
 	bool restoreOnNextMove, resetPositionOnNextMove, receivedFirstResize, isMaximised;
-	bool hovering, activated;
+	bool hovering, activated, appearActivated;
 	bool visualizeRepaints, visualizeLayoutBounds, visualizePaintSteps; // Inspector properties.
 
 	EsElement *mainPanel, *toolbar;
@@ -919,7 +919,7 @@ EsWindow *EsWindowCreate(EsInstance *instance, EsWindowStyle style) {
 		EsSyscall(ES_SYSCALL_WINDOW_MOVE, window->handle, (uintptr_t) &bounds, 0, ES_FLAGS_DEFAULT);
 		EsSyscall(ES_SYSCALL_WINDOW_SET_PROPERTY, window->handle, 0, 0, ES_WINDOW_PROPERTY_FOCUSED);
 		window->mainPanel = EsPanelCreate(window, ES_ELEMENT_NON_CLIENT | ES_CELL_FILL, ES_STYLE_PANEL_CONTAINER_WINDOW_ROOT);
-		window->SetStyle(ES_STYLE_CONTAINER_WINDOW_ACTIVE);
+		window->SetStyle(ES_STYLE_CONTAINER_WINDOW);
 		EsMessage m = { .type = ES_MSG_UI_SCALE_CHANGED };
 		EsMessageSend(window, &m);
 	} else if (style == ES_WINDOW_INSPECTOR) {
@@ -1799,6 +1799,8 @@ bool EsElement::RefreshStyleState() {
 
 	if (flags & ES_ELEMENT_DISABLED) {
 		styleStateFlags |= THEME_PRIMARY_STATE_DISABLED;
+	} else if (window && !window->activated && !window->appearActivated) {
+		styleStateFlags |= THEME_PRIMARY_STATE_INACTIVE;
 	} else {
 		if (((state & UI_STATE_LEFT_PRESSED) && ((state & UI_STATE_HOVERED) || gui.draggingStarted || (state & UI_STATE_STRONG_PRESSED))) 
 				|| (state & UI_STATE_MENU_SOURCE)) {
@@ -5917,6 +5919,14 @@ void UIScaleChanged(EsElement *element, EsMessage *message) {
 	}
 }
 
+void UIMaybeRefreshStyleAll(EsElement *element) {
+	element->MaybeRefreshStyle();
+
+	for (uintptr_t i = 0; i < element->children.Length(); i++) {
+		UIMaybeRefreshStyleAll(element->children[i]);
+	}
+}
+
 void EsElementGetSize(EsElement *element, int *width, int *height) {
 	EsMessageMutexCheck();
 
@@ -6884,10 +6894,6 @@ void UIProcessWindowManagerMessage(EsWindow *window, EsMessage *message, Process
 
 		if (window->windowStyle == ES_WINDOW_MENU) {
 			window->Destroy();
-		} else if (window->windowStyle == ES_WINDOW_CONTAINER) {
-			// Redraw window borders.
-			window->SetStyle(ES_STYLE_CONTAINER_WINDOW_INACTIVE);
-			window->Repaint(true);
 		}
 
 		window->activated = false;
@@ -6901,6 +6907,7 @@ void UIProcessWindowManagerMessage(EsWindow *window, EsMessage *message, Process
 		}
 
 		EsMessageSend(window, message);
+		UIMaybeRefreshStyleAll(window);
 	} else if (message->type == ES_MSG_WINDOW_ACTIVATED) {
 		AccessKeyModeExit();
 
@@ -6911,12 +6918,6 @@ void UIProcessWindowManagerMessage(EsWindow *window, EsMessage *message, Process
 		EsMessage m = { ES_MSG_WINDOW_ACTIVATED };
 		EsMessageSend(window, &m);
 
-		if (window->windowStyle == ES_WINDOW_CONTAINER) {
-			// Redraw window borders.
-			window->SetStyle(ES_STYLE_CONTAINER_WINDOW_ACTIVE);
-			window->Repaint(true);
-		}
-
 		if (!window->focused && window->inactiveFocus) {
 			EsElementFocus(window->inactiveFocus, false);
 			window->inactiveFocus->Repaint(true);
@@ -6924,6 +6925,7 @@ void UIProcessWindowManagerMessage(EsWindow *window, EsMessage *message, Process
 		}
 
 		UIRefreshPrimaryClipboard(window);
+		UIMaybeRefreshStyleAll(window);
 	}
 
 	skipInputMessage:;
diff --git a/desktop/settings.cpp b/desktop/settings.cpp
index a4943b7..3a89c1a 100644
--- a/desktop/settings.cpp
+++ b/desktop/settings.cpp
@@ -538,6 +538,8 @@ void SettingsPageKeyboard(EsElement *element, SettingsPage *page) {
 }
 
 void SettingsPageDisplay(EsElement *element, SettingsPage *page) {
+	// TODO.
+
 	EsElementSetHidden(((SettingsInstance *) element->instance)->undoButton, false);
 
 	EsPanel *content = EsPanelCreate(element, ES_CELL_FILL | ES_PANEL_V_SCROLL_AUTO, &styleNewTabContent);
@@ -554,6 +556,49 @@ void SettingsPageDisplay(EsElement *element, SettingsPage *page) {
 			100, 400, INTERFACE_STRING(CommonUnitPercent), 0.05, 5);
 }
 
+void SettingsPageTheme(EsElement *element, SettingsPage *page) {
+	// TODO.
+
+	EsElementSetHidden(((SettingsInstance *) element->instance)->undoButton, false);
+
+	EsPanel *content = EsPanelCreate(element, ES_CELL_FILL | ES_PANEL_V_SCROLL_AUTO, &styleNewTabContent);
+	EsPanel *container = EsPanelCreate(content, ES_PANEL_VERTICAL | ES_CELL_H_SHRINK, &styleSettingsGroupContainer2);
+	SettingsAddTitle(container, page);
+
+	EsPanel *warningRow = EsPanelCreate(container, ES_CELL_H_CENTER | ES_PANEL_HORIZONTAL, &styleSettingsTable);
+	EsIconDisplayCreate(warningRow, ES_FLAGS_DEFAULT, 0, ES_ICON_DIALOG_WARNING);
+	EsTextDisplayCreate(warningRow, ES_FLAGS_DEFAULT, 0, "Work in progress" ELLIPSIS);
+
+	EsPanel *table = EsPanelCreate(container, ES_CELL_H_FILL | ES_PANEL_TABLE | ES_PANEL_HORIZONTAL, &styleSettingsTable);
+	EsPanelSetBands(table, 2);
+	EsTextDisplayCreate(table, ES_CELL_H_RIGHT, 0, "Wallpaper:", -1); 
+	EsTextbox *textbox = EsTextboxCreate(table, ES_CELL_H_LEFT | ES_CELL_H_PUSH | ES_TEXTBOX_EDIT_BASED | ES_ELEMENT_FREE_USER_DATA, ES_STYLE_TEXTBOX_BORDERED_SINGLE);
+
+	textbox->messageUser = [] (EsElement *element, EsMessage *message) {
+		if (message->type == ES_MSG_TEXTBOX_EDIT_END) {
+			EsMutexAcquire(&api.systemConfigurationMutex);
+
+			EsSystemConfigurationGroup *group = SystemConfigurationGetGroup("general", -1, true);
+
+			if (group) {
+				EsSystemConfigurationItem *item = SystemConfigurationGetItem(group, "wallpaper", -1, true);
+
+				if (item) {
+					EsHeapFree(item->value);
+					item->value = EsTextboxGetContents((EsTextbox *) element, &item->valueBytes);
+					desktop.configurationModified = true;
+					EsThreadCreate(WallpaperLoad, nullptr, 0);
+				}
+			}
+
+			EsMutexRelease(&api.systemConfigurationMutex);
+			return ES_HANDLED;
+		}
+
+		return 0;
+	};
+}
+
 SettingsPage settingsPages[] = {
 	{ INTERFACE_STRING(DesktopSettingsAccessibility), ES_ICON_PREFERENCES_DESKTOP_ACCESSIBILITY, SettingsPageUnimplemented, 'A' }, // TODO.
 	{ INTERFACE_STRING(DesktopSettingsDateAndTime), ES_ICON_PREFERENCES_SYSTEM_TIME, SettingsPageUnimplemented, 'C' }, // TODO.
@@ -564,7 +609,7 @@ SettingsPage settingsPages[] = {
 	{ INTERFACE_STRING(DesktopSettingsNetwork), ES_ICON_PREFERENCES_SYSTEM_NETWORK, SettingsPageUnimplemented, 'H' }, // TODO.
 	{ INTERFACE_STRING(DesktopSettingsPower), ES_ICON_PREFERENCES_SYSTEM_POWER, SettingsPageUnimplemented, 'J' }, // TODO.
 	{ INTERFACE_STRING(DesktopSettingsSound), ES_ICON_PREFERENCES_DESKTOP_SOUND, SettingsPageUnimplemented, 'K' }, // TODO.
-	{ INTERFACE_STRING(DesktopSettingsTheme), ES_ICON_APPLICATIONS_INTERFACEDESIGN, SettingsPageUnimplemented, 'M' }, // TODO.
+	{ INTERFACE_STRING(DesktopSettingsTheme), ES_ICON_APPLICATIONS_INTERFACEDESIGN, SettingsPageTheme, 'M' },
 };
 
 void SettingsButtonPressed(EsInstance *_instance, EsElement *element, EsCommand *) {
diff --git a/desktop/styles.header b/desktop/styles.header
index 35fd5c6..ace1382 100644
--- a/desktop/styles.header
+++ b/desktop/styles.header
@@ -16,8 +16,7 @@ define_private ES_STYLE_COLOR_CIRCLE (ES_STYLE_CAST(1243))
 define_private ES_STYLE_COLOR_HEX_TEXTBOX (ES_STYLE_CAST(1245))
 define_private ES_STYLE_COLOR_PICKER_MAIN_PANEL (ES_STYLE_CAST(1247))
 define_private ES_STYLE_COLOR_SLIDER (ES_STYLE_CAST(1249))
-define_private ES_STYLE_CONTAINER_WINDOW_ACTIVE (ES_STYLE_CAST(1251))
-define_private ES_STYLE_CONTAINER_WINDOW_INACTIVE (ES_STYLE_CAST(1255))
+define_private ES_STYLE_CONTAINER_WINDOW (ES_STYLE_CAST(1251))
 define_private ES_STYLE_CURSOR_LOCATOR (ES_STYLE_CAST(1591))
 define ES_STYLE_DIALOG_BUTTON_AREA (ES_STYLE_CAST(1259))
 define ES_STYLE_DIALOG_CONTENT (ES_STYLE_CAST(1261))
diff --git a/desktop/theme.cpp b/desktop/theme.cpp
index c77d96e..ae1abd3 100644
--- a/desktop/theme.cpp
+++ b/desktop/theme.cpp
@@ -28,6 +28,7 @@
 #define THEME_PRIMARY_STATE_HOVERED  (2)
 #define THEME_PRIMARY_STATE_PRESSED  (3)
 #define THEME_PRIMARY_STATE_DISABLED (4)
+#define THEME_PRIMARY_STATE_INACTIVE (5) // When the window has been deactivated.
 #define THEME_PRIMARY_STATE_MASK (0x000F)
 
 #define THEME_STATE_FOCUSED        (1 << 15)
diff --git a/res/Theme Source.dat b/res/Theme Source.dat
index 979c0ec..d86a5d9 100644
Binary files a/res/Theme Source.dat and b/res/Theme Source.dat differ
diff --git a/res/Themes/Theme.dat b/res/Themes/Theme.dat
index 707549d..6db90e4 100644
Binary files a/res/Themes/Theme.dat and b/res/Themes/Theme.dat differ
diff --git a/util/designer/designer.c b/util/designer/designer.c
index 119b09b..ac8b732 100644
--- a/util/designer/designer.c
+++ b/util/designer/designer.c
@@ -207,6 +207,7 @@ UIButton *previewPrimaryStateIdle;
 UIButton *previewPrimaryStateHovered;
 UIButton *previewPrimaryStatePressed;
 UIButton *previewPrimaryStateDisabled;
+UIButton *previewPrimaryStateInactive;
 UIButton *previewStateFocused;
 UIButton *previewStateChecked;
 UIButton *previewStateIndeterminate;
@@ -5507,6 +5508,9 @@ int main(int argc, char **argv)
 				previewPrimaryStateDisabled = UIButtonCreate(0, UI_BUTTON_SMALL, "Disabled", -1);
 				previewPrimaryStateDisabled->invoke = PreviewSetPrimaryState;
 				previewPrimaryStateDisabled->e.cp = (void *) PRIMARY_STATE_DISABLED;
+				previewPrimaryStateInactive = UIButtonCreate(0, UI_BUTTON_SMALL, "Inactive", -1);
+				previewPrimaryStateInactive->invoke = PreviewSetPrimaryState;
+				previewPrimaryStateInactive->e.cp = (void *) PRIMARY_STATE_INACTIVE;
 			UIParentPop();
 
 			UIPanelCreate(0, UI_PANEL_HORIZONTAL | UI_ELEMENT_PARENT_PUSH);
diff --git a/util/designer/designer.rf b/util/designer/designer.rf
index 6fa7436..70302fc 100644
--- a/util/designer/designer.rf
+++ b/util/designer/designer.rf
@@ -294,6 +294,7 @@ enum PrimaryState_Type StyleEnumOp {
 	PRIMARY_STATE_HOVERED #StringOption { "Hovered" };
 	PRIMARY_STATE_PRESSED #StringOption { "Pressed" };
 	PRIMARY_STATE_DISABLED #StringOption { "Disabled" };
+	PRIMARY_STATE_INACTIVE #StringOption { "Inactive" };
 };
 
 struct Sequence Sequence_Type RfStructOp {