Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt	(revision 54214)
+++ CMakeLists.txt	(working copy)
@@ -166,6 +166,7 @@
 
 if(UNIX AND NOT APPLE)
 	option(WITH_X11_XINPUT "Enable X11 Xinput (tablet support and unicode input)"	ON)
+	option(WITH_X11_XINERAMA "Enable multi-head support"	ON)
 	option(WITH_X11_XF86VMODE "Enable X11 video mode switching"	ON)
 	option(WITH_SYSTEM_GLEW "Use GLEW OpenGL wrapper library provided by the operating system" ON)
 
@@ -414,6 +415,7 @@
 	set(WITH_GHOST_XDND OFF)
 	set(WITH_X11_XF86VMODE OFF)
 	set(WITH_X11_XINPUT OFF)
+	set(WITH_X11_XINERAMA OFF)
 endif()
 
 if(MINGW)
@@ -800,6 +802,10 @@
 			set(PLATFORM_LINKLIBS "${PLATFORM_LINKLIBS} ${X11_Xinput_LIB}")
 		endif()
 
+		if(WITH_X11_XINERAMA)
+			set(PLATFORM_LINKLIBS "${PLATFORM_LINKLIBS} ${X11_Xinerama_LIB}")
+		endif()
+
 		if(WITH_X11_XF86VMODE)
 			# XXX, why dont cmake make this available?
 			FIND_LIBRARY(X11_Xxf86vmode_LIB Xxf86vm   ${X11_LIB_SEARCH_PATH})
Index: intern/ghost/CMakeLists.txt
===================================================================
--- intern/ghost/CMakeLists.txt	(revision 54214)
+++ intern/ghost/CMakeLists.txt	(working copy)
@@ -273,6 +273,10 @@
 		add_definitions(-DWITH_X11_XINPUT)
 	endif()
 
+	if(WITH_X11_XINERAMA)
+		add_definitions(-DWITH_X11_XINERAMA)
+	endif()
+
 elseif(WIN32)
 	## Warnings as errors, this is too strict!
 	#if(MSVC)
Index: intern/ghost/intern/GHOST_SystemX11.cpp
===================================================================
--- intern/ghost/intern/GHOST_SystemX11.cpp	(revision 54214)
+++ intern/ghost/intern/GHOST_SystemX11.cpp	(working copy)
@@ -50,6 +50,10 @@
 #  include "GHOST_DropTargetX11.h"
 #endif
 
+#ifdef WITH_X11_XINERAMA
+#  include "X11/extensions/Xinerama.h"
+#endif
+
 #include "GHOST_Debug.h"
 
 #include <X11/Xatom.h>
@@ -237,6 +241,32 @@
 		GHOST_TUns32& height) const
 {
 	if (m_display) {
+
+#ifdef WITH_X11_XINERAMA
+		/* NOTE, no way to select a primary monitor, uses the first */
+		bool success = false;
+		int dummy1, dummy2;
+		if (XineramaQueryExtension(m_display, &dummy1, &dummy2)) {
+			if (XineramaIsActive(m_display)) {
+				int heads = 0;
+				XineramaScreenInfo *p = XineramaQueryScreens(m_display, &heads);
+				if (heads > 0) {
+					for (int x = 0; x < heads; x++) {
+						width = p[x].width;
+						height = p[x].height;
+						break;
+					}
+					success = true;
+				}
+				XFree(p);
+			}
+		}
+
+		if (success) {
+			return;
+		}
+#endif
+
 		width  = DisplayWidth(m_display, DefaultScreen(m_display));
 		height = DisplayHeight(m_display, DefaultScreen(m_display));
 	}