diff --git a/Adafruit_SPITFT.cpp b/Adafruit_SPITFT.cpp
index c7cea2e..b48482a 100644
--- a/Adafruit_SPITFT.cpp
+++ b/Adafruit_SPITFT.cpp
@@ -164,6 +164,24 @@ void Adafruit_SPITFT::spiWrite(uint8_t b) {
  * Transaction API
  * */
 
+void Adafruit_SPITFT::setAddrWindow(uint16_t x, uint16_t y, uint16_t w, uint16_t h) {
+  x += _xstart;
+  y += _ystart;
+  uint32_t xa = ((uint32_t)x << 16) | (x+w-1);
+  uint32_t ya = ((uint32_t)y << 16) | (y+h-1); 
+
+  //Serial.print("X: "); Serial.println(xa, HEX);
+  //Serial.print("Y: "); Serial.println(ya, HEX);
+
+  writeCommand(xSetCommand); // Column addr set
+  SPI_WRITE32(xa);
+
+  writeCommand(ySetCommand); // Row addr set
+  SPI_WRITE32(ya);
+
+  writeCommand(RAMwriteCommand); // write to RAM
+}
+
 void inline Adafruit_SPITFT::startWrite(void){
     SPI_BEGIN_TRANSACTION();
     SPI_CS_LOW();
@@ -297,6 +315,13 @@ void Adafruit_SPITFT::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,
     endWrite();
 }
 
+
+void Adafruit_SPITFT::invertDisplay(boolean i) {
+  startWrite();
+  writeCommand(i ? invertOnCommand : invertOffCommand);
+  endWrite();
+}
+
 // Adapted from https://github.com/PaulStoffregen/ILI9341_t3
 // by Marc MERLIN. See examples/pictureEmbed to use this.
 // 5/6/2017: function name and arguments have changed for compatibility
diff --git a/Adafruit_SPITFT.h b/Adafruit_SPITFT.h
index 0024a01..1173c04 100644
--- a/Adafruit_SPITFT.h
+++ b/Adafruit_SPITFT.h
@@ -42,7 +42,7 @@ class Adafruit_SPITFT : public Adafruit_GFX {
         void      writeFastHLine(int16_t x, int16_t y, int16_t w, uint16_t color);
 
         // Transaction API not used by GFX
-	virtual   void setAddrWindow(uint16_t x, uint16_t y, uint16_t w, uint16_t h) = 0;
+	void      setAddrWindow(uint16_t x, uint16_t y, uint16_t w, uint16_t h);
         void      writePixel(uint16_t color);
         void      writePixels(uint16_t * colors, uint32_t len);
         void      writeColor(uint16_t color, uint32_t len);
@@ -56,6 +56,7 @@ class Adafruit_SPITFT : public Adafruit_GFX {
         using     Adafruit_GFX::drawRGBBitmap; // Check base class first
         void      drawRGBBitmap(int16_t x, int16_t y,
                     uint16_t *pcolors, int16_t w, int16_t h);
+	void      invertDisplay(boolean i);
 
         uint16_t  color565(uint8_t r, uint8_t g, uint8_t b);
 
@@ -75,6 +76,10 @@ class Adafruit_SPITFT : public Adafruit_GFX {
         void        writeCommand(uint8_t cmd);
         void        spiWrite(uint8_t v);
         uint8_t     spiRead(void);
+
+	uint8_t   invertOnCommand = 0, invertOffCommand = 0;
+	uint8_t   ySetCommand, xSetCommand, RAMwriteCommand;
+	int16_t   _xstart = 0, _ystart = 0;
 };
 
 #endif