diff --git a/gfxconf.example.h b/gfxconf.example.h
index 6b2f6d9d..52c129ef 100644
--- a/gfxconf.example.h
+++ b/gfxconf.example.h
@@ -40,6 +40,7 @@
 //    #define INTERRUPTS_ON()                          optional_code
 
 // Options that (should where relevant) apply to all operating systems
+//    #define GFX_COMPILER                             GFX_COMPILER_UNKNOWN
 //    #define GFX_NO_OS_INIT                           FALSE
 //    #define GFX_OS_EXTRA_INIT_FUNCTION               myOSInitRoutine
 //    #define GFX_OS_EXTRA_DEINIT_FUNCTION             myOSDeInitRoutine
diff --git a/src/gdisp/gdisp.c b/src/gdisp/gdisp.c
index 86931952..377ccddb 100644
--- a/src/gdisp/gdisp.c
+++ b/src/gdisp/gdisp.c
@@ -1259,7 +1259,7 @@ void gdispGBlitArea(GDisplay *g, coord_t x, coord_t y, coord_t cx, coord_t cy, c
 			{
 				if (x < 0) { cx += x; x = 0; }
 				if (y < 0) { cy += y; y = 0; }
-				if (cx <= 0 || cy <= 0 || x >= g->g.Width || y >= g->g.Height) { MUTEX_EXIT(g); return; }
+				if (cx <= 0 || cy <= 0 || x >= g->g.Width || y >= g->g.Height) { x = y = cx = cy = 0; }
 				g->clipx0 = x;
 				g->clipy0 = y;
 				g->clipx1 = x+cx;	if (g->clipx1 > g->g.Width) g->clipx1 = g->g.Width;
diff --git a/src/gos/gos_arduino.c b/src/gos/gos_arduino.c
index 0c01a30c..380d528a 100644
--- a/src/gos/gos_arduino.c
+++ b/src/gos/gos_arduino.c
@@ -229,18 +229,19 @@ void gfxSleepMicroseconds(delaytime_t ms) {
  * For those it doesn't - read the compiler manuals and the library source code to
  * work out the correct macro values.
  * You can use the debugger to work out the values for your compiler and put them here.
- * Defining these macros as constant values makes the system behaviour guaranteed but also
- * makes your code compiler and cpu architecture dependant.
+ * Defining these macros as constant values makes the system behavior guaranteed but also
+ * makes your code compiler and cpu architecture dependent. It also saves a heap of code
+ * and a few bytes of RAM.
  */
-#if 0
-	// Define your compiler constant values here.
-	//	These example values are for mingw32 compiler (x86).
+#if GFX_COMPILER == GFX_COMPILER_MINGW32
 	#define AUTO_DETECT_MASK	FALSE
 	#define STACK_DIR_UP		FALSE
 	#define MASK1				0x00000011
 	#define MASK2				0x00000000
 	#define STACK_BASE			12
 #else
+	// Use auto-detection of the stack frame format
+	// Assumes all the relevant stuff to be relocated is in the first 256 bytes of the jmpbuf.
 	#define AUTO_DETECT_MASK	TRUE
 	#define STACK_DIR_UP		stackdirup			// TRUE if the stack grow up instead of down
 	#define MASK1				jmpmask1			// The 1st mask of jmp_buf elements that need relocation
diff --git a/src/gos/gos_options.h b/src/gos/gos_options.h
index 2f896508..8fb4f51b 100644
--- a/src/gos/gos_options.h
+++ b/src/gos/gos_options.h
@@ -82,6 +82,18 @@
  * @name    GOS Optional Parameters
  * @{
  */
+	/**
+	 * @brief	Enable compiler specific code
+	 * @details	Defaults to GFX_COMPILER_UNKNOWN
+	 * @note	This is setting enables optimisations that are compiler specific. It does
+	 * 			not need to be specified as reasonable defaults and various auto-detection
+	 * 			will happen as required.
+	 */
+	#ifndef GFX_COMPILER
+		#define GFX_COMPILER			GFX_COMPILER_UNKNOWN
+	#endif
+	#define GFX_COMPILER_UNKNOWN		0		// Unknown compiler
+	#define GFX_COMPILER_MINGW32		1		// MingW32 (x86) compiler for windows
  	/**
  	 * @brief	Should uGFX avoid initializing the operating system
  	 * @details	Defaults to FALSE
diff --git a/src/gos/gos_raw32.c b/src/gos/gos_raw32.c
index 529dcf79..085c3c5d 100644
--- a/src/gos/gos_raw32.c
+++ b/src/gos/gos_raw32.c
@@ -440,17 +440,18 @@ void gfxSleepMicroseconds(delaytime_t ms) {
 	 * work out the correct macro values.
 	 * You can use the debugger to work out the values for your compiler and put them here.
 	 * Defining these macros as constant values makes the system behavior guaranteed but also
-	 * makes your code compiler and cpu architecture dependent.
+	 * makes your code compiler and cpu architecture dependent. It also saves a heap of code
+	 * and a few bytes of RAM.
 	 */
-	#if 0
-		// Define your compiler constant values here.
-		//	These example values are for mingw32 compiler (x86).
+	#if GFX_COMPILER == GFX_COMPILER_MINGW32
 		#define AUTO_DETECT_MASK	FALSE
 		#define STACK_DIR_UP		FALSE
 		#define MASK1				0x00000011
 		#define MASK2				0x00000000
 		#define STACK_BASE			12
 	#else
+		// Use auto-detection of the stack frame format
+		// Assumes all the relevant stuff to be relocated is in the first 256 bytes of the jmpbuf.
 		#define AUTO_DETECT_MASK	TRUE
 		#define STACK_DIR_UP		stackdirup			// TRUE if the stack grow up instead of down
 		#define MASK1				jmpmask1			// The 1st mask of jmp_buf elements that need relocation