diff --git a/source/Platform/Unix/X11Display.cpp b/source/Platform/Unix/X11Display.cpp
index 8b87b2e..d255d58 100644
--- a/source/Platform/Unix/X11Display.cpp
+++ b/source/Platform/Unix/X11Display.cpp
@@ -2,6 +2,8 @@
 #include <cstring>
 #include <Spectre/System/Log.h>
 #include <Spectre/Graphics/Image.h>
+#include <X11/Xatom.h>
+#include "XRandR.h"
 #include "X11WindowEventHandler.h"
 #include "Xlib.h"
 #include "wm_hints.h"
@@ -238,14 +240,75 @@ void X11Display::maximize()
 
 void X11Display::enterFullscreen(DisplayMode mode)
 {
+	if (!XRandR::FindMode(Xlib::getDisplay(), mode.width, mode.height, mode.bpp, &m_fullscreen_mode.size, &m_fullscreen_mode.rate)) {
+		Log::warn("X11: Failed to find a mode");
+		return;
+	}
 
+	toggleFullscreen(true);
+}
+
+void X11Display::toggleFullscreen(bool enable)
+{
+	::Display* disp = Xlib::getDisplay();
+	::Window                  root;
+	::XRRScreenConfiguration  *conf;
+	XRandR::VideoMode *mode = &m_desktop_mode;
+
+	root = RootWindow(disp, 0);
+	conf = XRRGetScreenInfo(disp, root);
+
+	if (enable) {
+		if (m_desktop_mode.rate < 1) {
+			Rotation r;
+			m_desktop_mode.rate = XRRConfigCurrentRate(conf);
+			m_desktop_mode.size = XRRConfigCurrentConfiguration(conf, &r);
+		}
+
+		mode = &m_fullscreen_mode;
+	}
+
+	wm_fullscreen(enable);
+	XRRSetScreenConfigAndRate(disp, conf, root, mode->size, RR_Rotate_0, mode->rate, CurrentTime);
 }
 
 void X11Display::exitFullscreen()
 {
-
+	if (m_fullscreen_mode.rate > 0) {
+		toggleFullscreen(false);
+		m_fullscreen_mode.rate = 0;
+		m_fullscreen_mode.size = 0;
+		m_desktop_mode.rate = 0;
+		m_desktop_mode.size = 0;
+	}
 }
 
+#define _NET_WM_STATE_REMOVE        0    /* remove/unset property */
+#define _NET_WM_STATE_ADD           1    /* add/set property */
+
+void X11Display::wm_fullscreen(bool enabled) {
+
+	::Display* disp = sp::Xlib::getDisplay();
+
+	XEvent xev;
+	Atom wm_state = sp::Xlib::getAtom("_NET_WM_STATE", False);
+	Atom wm_fs = sp::Xlib::getAtom("_NET_WM_STATE_FULLSCREEN", False);
+
+	memset(&xev, 0, sizeof(xev));
+	xev.type = ClientMessage;
+	xev.xclient.window = m_win;
+	xev.xclient.message_type = wm_state;
+	xev.xclient.format = 32;
+	xev.xclient.data.l[0] = enabled ? _NET_WM_STATE_ADD : _NET_WM_STATE_REMOVE;
+	xev.xclient.data.l[1] = wm_fs;
+	xev.xclient.data.l[2] = 0;
+
+	::XSendEvent(disp, ::XDefaultRootWindow(disp), False,
+		SubstructureRedirectMask | SubstructureNotifyMask,
+		&xev);
+}
+
+
 void X11Display::setCaption(const std::string& caption)
 {
 	::XStoreName(Xlib::getDisplay(), m_win, caption.c_str());
@@ -329,10 +392,19 @@ void X11Display::processEvent(const ::XEvent& event)
 	case FocusIn:
 		Log::debug("X11: FocusIn");
 		_priv::focused_display = this;
+
+		if (m_fullscreen_mode.rate > 0) {
+			toggleFullscreen(true);
+		}
+
 		break;
 	case FocusOut:
 		Log::debug("X11: FocusOut");
 		_priv::focused_display = NULL;
+		if (m_fullscreen_mode.rate > 0) {
+			toggleFullscreen(false);
+			minimize();
+		}
 		break;
 	}
 }
diff --git a/source/Platform/Unix/X11Display.h b/source/Platform/Unix/X11Display.h
index ae2d327..2c2ca79 100644
--- a/source/Platform/Unix/X11Display.h
+++ b/source/Platform/Unix/X11Display.h
@@ -7,6 +7,7 @@
 #include <X11/Xos.h>
 #include <cstdint>
 #include <Platform/PlatformDisplay.h>
+#include "Xrandr.h"
 
 namespace sp {
 
@@ -62,6 +63,10 @@ protected :
 
 	void			createHiddenCursor();
 
+	void 			toggleFullscreen(bool enabled);
+
+	void 			wm_fullscreen(bool enabled);
+
 protected :
 
 	::Window		m_win;
@@ -72,6 +77,10 @@ protected :
 	::Cursor		m_cur_last;
 
 	Vector2u	m_size;
+
+	XRandR::VideoMode	m_fullscreen_mode;
+
+	XRandR::VideoMode	m_desktop_mode;
 };
 
 } // namespace sp