diff --git a/common/app/app.c b/common/app/app.c
index f333d78..cb7bcf9 100644
--- a/common/app/app.c
+++ b/common/app/app.c
@@ -2,291 +2,23 @@
 #include "tft.h"
 #include "system.h"
 #include "touch.h"
-#include "button.h"
-#include "checkbox.h"
-#include "pixy.h"
-#include <stdio.h>
-#include <stdlib.h>
+#include "screen_main.h"
 
 
-bool pixy_connected = false;
-
-/*TOUCH_AREA_STRUCT a1;
-
-void touchCB(void* touchArea, TOUCH_ACTION triggeredAction) {
-	
-	switch(triggeredAction) {
-		case PEN_DOWN:
-			printf("action PEN_DOWN\n");
-		break;
-
-		case PEN_UP:
-			printf("action PEN_UP\n");
-		break;
-		case PEN_MOVE:
-			printf("action PEN_MOVE\n");
-		break;
-		case PEN_ENTER:
-			printf("action PEN_ENTER\n");
-		break;
-		case PEN_LEAVE:
-			printf("action PEN_LEAVE\n");
-		break;
-		default:	
-		printf("action %s\n",triggeredAction);
-		break;
-	}
-}*/
-
-BUTTON_STRUCT b1;
-
-void buttonCB(void* button) {
-	printf("button pressed\n");
-}
-
-CHECKBOX_STRUCT c1;
-
-void checkboxCB(void *checkbox, bool checked) {
-	printf("Checkbox %s\n",(checked?"checked":"unchecked"));
-}
-
 void app_init() {
 	system_init();
 	tft_init();
 	touch_init();
 
-	pixy_connected = (pixy_init()==0); //try to connect to pixy
-		
-	//only testwise
-	tft_clear(WHITE);	
-	tft_draw_pixel(10,210,BLUE);
-	tft_draw_pixel(12,210,BLUE);
-	tft_draw_rectangle(40,210,60,235,BLUE);
-	tft_fill_rectangle(100,215,200,225,GREEN);
-	tft_draw_line(10,215,310,225,RGB(0xFF,0,0xFF));
-    	tft_draw_circle(10,10,100, RED);
-
-	/*a1.hookedActions = PEN_DOWN | PEN_UP | PEN_MOVE | PEN_ENTER | PEN_LEAVE;
-	a1.x1 = 30;
-        a1.y1 = 30;
-        a1.x2 = 100;
-        a1.y2 = 60;
-        a1.callback = touchCB;
-	touch_register_area(&a1);
-
-	tft_draw_rectangle(30,30,100,60,BLUE);
-	tft_print_line(30, 30, RED, BLUE, 0, "Hallo");*/
-
-        //button test
-	b1.base.x1=25; //Start X of Button
-        b1.base.y1=45; //Start Y of Button
-        b1.base.x2=AUTO; //b1.base.x1+160; //Auto Calculate X2 with String Width
-        b1.base.y2=AUTO; //Auto Calculate Y2 with String Height
-        b1.txtcolor=WHITE; //Set foreground color
-        b1.bgcolor=HEX(0xDE1010); //Set background color (Don't take 255 or 0 on at least one channel, to make shadows possible)
-        b1.font=0; //Select Font
-        b1.text="Hallo"; //Set Text (For formatted strings take sprintf)
-        b1.callback=buttonCB; //Call b1_cb as Callback
-        gui_button_add(&b1); //Register Button (and run the callback from now on)
-
-	//Checkbox test
-	c1.base.x1=220;
-	c1.base.y1=45;
-	c1.base.x2=c1.base.x1+16;
-	c1.base.y2=c1.base.y1+16;
-	c1.fgcolor = GREEN;
-	c1.checked = true;	
-	c1.callback = checkboxCB;
-	gui_checkbox_add(&c1);
-
+	gui_screen_navigate(get_screen_main());
 }
 
 
-
-
-int pixy_led_test();
-int pixy_frame_test();
-
 //app event loop
 void app_process() {
 	
 	system_process(); //Let the system handle it's pending events
-	//gui_button_redraw(&b1);
-	///gui_checkbox_redraw(&c1);
-
-	//Note: The only way to detect that pixy has been disconnected is if a command fails. There's no pixy_is_connected method yet :'(
-
-	if(!pixy_connected) { //Pixy not connected
-		pixy_close(); //Ensure that all pixy resources are freed (failsafe)
-		if(pixy_init()==0) { //try to connect to pixy
-			pixy_connected=true;
-		}
-	}
-
-	if(pixy_connected) {
-		pixy_service(); //Send/receive event data from/to pixy failed
-
-		//Code for tests see below
-		if(pixy_led_test()!=0) {
-			pixy_connected=false;
-		}
-			
-		/*if(pixy_frame_test()!=0) {
-			 pixy_connected=false;
-	        }*/
-		system_delay(500);
-	}
+	gui_screen_update(); //update the currently active screen
 }
 
 
-//-----------------------------------------------------------------------------------------------------------------
-
-int colorind;
-const uint32_t colors [] = {0xFF0000, 0x00FF00,0x0000FF,0xFFFF00,0x00FFFF,0xFF00FF,0xFFFFFF,0x000000};
-const int num_colors = sizeof(colors)/sizeof(uint32_t);
-
-int pixy_led_test() {
-        if(colorind==0) {
-                pixy_led_set_max_current(5);
-        }
-
-        int32_t response;
-        int return_value;
-        return_value = pixy_command("led_set", INT32(colors[colorind++]), END_OUT_ARGS,  &response, END_IN_ARGS);
-        colorind%=num_colors;
-
-	if(return_value!=0) {
-		colorind=0; //reset color ind, to start at zero when plugging pixy in again
-	}
-
-	return return_value;
-}
-
-//----------------------------------------------------------------------------------------------------------------------------
-
-int renderBA81(uint8_t renderFlags, uint16_t width, uint16_t height, uint32_t frameLen, uint8_t *frame);
-
-
-int pixy_frame_test() {
-
- uint8_t* videodata;
-      int32_t response;
-      int32_t fourccc;
-      int8_t renderflags;
-      uint16_t xwidth;
-      uint16_t ywidth;
-      uint32_t size;
-
-
-      int return_value = pixy_command("cam_getFrame",  // String id for remote procedure
-                                      INT8(0x21),     // mode
-                                      INT16(0),        // xoffset
-                                      INT16(0),         // yoffset
-                                      INT16(320),       // width
-                                      INT16(200),       // height
-                                      END_OUT_ARGS,              // separator
-                                      &response,      // pointer to mem address for return value
-                                      &fourccc,
-                                      &renderflags,
-                                      &xwidth,
-                                      &ywidth,
-                                      &size,
-                                      &videodata,        // pointer to mem address for returned frame
-                                      END_IN_ARGS);
-
-      if(return_value==0) {
-            return_value = renderBA81(renderflags,xwidth,ywidth,size,videodata);
-      } 
-
-      return return_value;
-}
-
-
-
-void interpolateBayer(uint16_t width, uint16_t x, uint16_t y, uint8_t *pixel, uint8_t* r, uint8_t* g, uint8_t* b)
-{
-    if (y&1)
-    {
-        if (x&1)
-        {
-            *r = *pixel;
-            *g = (*(pixel-1)+*(pixel+1)+*(pixel+width)+*(pixel-width))>>2;
-            *b = (*(pixel-width-1)+*(pixel-width+1)+*(pixel+width-1)+*(pixel+width+1))>>2;
-        }
-        else
-        {
-            *r = (*(pixel-1)+*(pixel+1))>>1;
-            *g = *pixel;
-            *b = (*(pixel-width)+*(pixel+width))>>1;
-        }
-    }
-    else
-    {
-        if (x&1)
-        {
-            *r = (*(pixel-width)+*(pixel+width))>>1;
-            *g = *pixel;
-            *b = (*(pixel-1)+*(pixel+1))>>1;
-        }
-        else
-        {
-            *r = (*(pixel-width-1)+*(pixel-width+1)+*(pixel+width-1)+*(pixel+width+1))>>2;
-            *g = (*(pixel-1)+*(pixel+1)+*(pixel+width)+*(pixel-width))>>2;
-            *b = *pixel;
-        }
-    }
-
-}
-
-
-
-int renderBA81(uint8_t renderFlags, uint16_t width, uint16_t height, uint32_t frameLen, uint8_t *frame)
-{
-    uint16_t x, y;
-    uint8_t r, g, b;
-
-
-    // skip first line
-    frame += width;
-
-    // don't render top and bottom rows, and left and rightmost columns because of color
-    // interpolation
-    //uint32_t decodedimage[(width-2)*(height-2)];
-    uint16_t* decodedimage = malloc(sizeof(uint16_t)*(width-2)*(height-2));
-   
-    if(decodedimage==NULL) { //not enough free space to decode image in memory
-        //decode & render image pixel by pixel
-	uint16_t* line = decodedimage;
-    	for (y=1; y<height-1; y++)
-        {
-                frame++;
-                for (x=1; x<width-1; x++, frame++)
-                {
-                    interpolateBayer(width, x, y, frame, &r, &g, &b);
-                    tft_draw_pixel(x-1,y-1,RGB(r,g,b));
-                }
-                frame++;
-         }
-    } else { //enough space  
-	    uint16_t* line = decodedimage;
-	    for (y=1; y<height-1; y++)
-	    {
-		//line = (unsigned int *)img.scanLine(y-1);
-		frame++;
-		for (x=1; x<width-1; x++, frame++)
-		{
-		    interpolateBayer(width, x, y, frame, &r, &g, &b);
-		    //*line++ = (0xff<<24) | (r<<16) | (g<<8) | (b<<0);
-		    *line++ = RGB(r,g,b);
-		}
-		frame++;
-	    }
-
-	    tft_draw_bitmap_unscaled(0,0,width-2,height-2,decodedimage); 
-	  
-	    free(decodedimage); 
-    }
-    
-    return 0;
-}
-
diff --git a/common/app/screen_guitest.c b/common/app/screen_guitest.c
new file mode 100644
index 0000000..f4f40cd
--- /dev/null
+++ b/common/app/screen_guitest.c
@@ -0,0 +1,119 @@
+#include "screen_guitest.h"
+#include "button.h"
+#include "tft.h"
+#include "checkbox.h"
+
+
+static BUTTON_STRUCT b_back;
+static TOUCH_AREA_STRUCT a_area;
+static CHECKBOX_STRUCT c_cbox;
+
+static void checkboxCB(void *checkbox, bool checked) {
+        printf("Checkbox %s\n",(checked?"checked":"unchecked"));
+}
+
+static void b_back_cb(void* button) {
+        gui_screen_back();
+}
+
+static void touchCB(void* touchArea, TOUCH_ACTION triggeredAction) {
+        
+        switch(triggeredAction) {
+                case PEN_DOWN:
+                        printf("action PEN_DOWN\n");
+                break;
+                case PEN_UP:
+                        printf("action PEN_UP\n");
+                break;
+                case PEN_MOVE:
+                        printf("action PEN_MOVE\n");
+                break;
+                case PEN_ENTER:
+                        printf("action PEN_ENTER\n");
+                break;
+                case PEN_LEAVE:
+                        printf("action PEN_LEAVE\n");
+                break;
+                default:        
+                printf("action %s\n",triggeredAction);
+                break;
+        }
+}
+
+static void enter(void* screen) {
+	tft_clear(HEX(0xA6FD9A));
+	
+	//Back button
+	b_back.base.x1=10; //Start X of Button
+        b_back.base.y1=10; //Start Y of Button
+        b_back.base.x2=AUTO; //b_back.base.x1+160; //Auto Calculate X2 with String Width
+        b_back.base.y2=AUTO; //Auto Calculate Y2 with String Height
+        b_back.txtcolor=WHITE; //Set foreground color
+        b_back.bgcolor=HEX(0xAE1010); //Set background color (Don't take 255 or 0 on at least one channel, to make shadows possible)
+        b_back.font=0; //Select Font
+        b_back.text="Back"; //Set Text (For formatted strings take sprintf)
+        b_back.callback=b_back_cb; //Call b_back_cb as Callback
+        gui_button_add(&b_back); //Register Button (and run the callback from now on)
+
+
+	//tft test
+	tft_draw_pixel(10,210,BLUE);
+        tft_draw_pixel(12,210,BLUE);
+        tft_draw_rectangle(40,100,60,235,BLUE);
+        tft_fill_rectangle(100,215,200,225,GREEN);
+        tft_draw_line(10,50,310,225,RGB(0xFF,0,0xFF));
+        tft_draw_circle(10,10,100, RED);
+        tft_print_line(30, 130, RED, BLUE, 0, "Hallo");
+	
+
+
+	//Area test
+	a_area.hookedActions = PEN_DOWN | PEN_UP | PEN_MOVE | PEN_ENTER | PEN_LEAVE;
+        a_area.x1 = 130;
+        a_area.y1 = 30;
+        a_area.x2 = 200;
+        a_area.y2 = 60;
+        a_area.callback = touchCB;
+        touch_register_area(&a_area);
+
+
+
+	 //Checkbox test
+        c_cbox.base.x1=220;
+        c_cbox.base.y1=45;
+        c_cbox.base.x2=c_cbox.base.x1+16;
+        c_cbox.base.y2=c_cbox.base.y1+16;
+        c_cbox.fgcolor = GREEN;
+        c_cbox.checked = true;
+        c_cbox.callback = checkboxCB;
+        gui_checkbox_add(&c_cbox);
+
+
+
+
+}
+
+static void leave(void* screen) {
+	gui_button_remove(&b_back);
+	gui_checkbox_remove(&c_cbox);
+	touch_unregister_area(&a_area);
+}
+
+static void update(void* screen) {
+	//gui_button_redraw(&b_back); //only needed if button is overdrawn by others
+	//.... for the other elements as well
+}
+
+
+static SCREEN_STRUCT screen = {
+	enter,
+	leave,
+	update
+};
+
+
+SCREEN_STRUCT* get_screen_guitest() {
+	return &screen;
+}
+
+
diff --git a/common/app/screen_guitest.h b/common/app/screen_guitest.h
new file mode 100644
index 0000000..97adfc9
--- /dev/null
+++ b/common/app/screen_guitest.h
@@ -0,0 +1,3 @@
+#include "screen.h"
+
+SCREEN_STRUCT* get_screen_guitest();
diff --git a/common/app/screen_main.c b/common/app/screen_main.c
new file mode 100644
index 0000000..b22dde4
--- /dev/null
+++ b/common/app/screen_main.c
@@ -0,0 +1,72 @@
+#include "screen_main.h"
+#include "screen_guitest.h"
+#include "screen_pixytest.h"
+#include "button.h"
+#include "tft.h"
+
+BUTTON_STRUCT b_guitest;
+BUTTON_STRUCT b_pixytest;
+
+
+static void b_guitest_cb(void* button) {
+	gui_screen_navigate(get_screen_guitest());
+}
+
+static void b_pixytest_cb(void* button) {
+	gui_screen_navigate(get_screen_pixytest());
+}
+
+
+static void enter(void* screen) {
+	tft_clear(WHITE);
+
+	//button to reach guitest
+	b_guitest.base.x1=25; //Start X of Button
+        b_guitest.base.y1=45; //Start Y of Button
+        b_guitest.base.x2=AUTO; //b_guitest.base.x1+160; //Auto Calculate X2 with String Width
+        b_guitest.base.y2=AUTO; //Auto Calculate Y2 with String Height
+        b_guitest.txtcolor=WHITE; //Set foreground color
+        b_guitest.bgcolor=HEX(0xDE1010); //Set background color (Don't take 255 or 0 on at least one channel, to make shadows possible)
+        b_guitest.font=0; //Select Font
+        b_guitest.text="Gui/Tft Test"; //Set Text (For formatted strings take sprintf)
+        b_guitest.callback=b_guitest_cb; //Call b_guitest_cb as Callback
+        gui_button_add(&b_guitest); //Register Button (and run the callback from now on)
+
+	//button to reach pixy test
+        b_pixytest.base.x1=200; //Start X of Button
+        b_pixytest.base.y1=45; //Start Y of Button
+        b_pixytest.base.x2=AUTO; //b_pixytest.base.x1+160; //Auto Calculate X2 with String Width
+        b_pixytest.base.y2=AUTO; //Auto Calculate Y2 with String Height
+        b_pixytest.txtcolor=BLUE; //Set foreground color
+        b_pixytest.bgcolor=HEX(0x10DE10); //Set background color (Don't take 255 or 0 on at least one channel, to make shadows possible)
+        b_pixytest.font=0; //Select Font
+        b_pixytest.text="Pixy Test"; //Set Text (For formatted strings take sprintf)
+        b_pixytest.callback=b_pixytest_cb; //Call b_pixytest_cb as Callback
+        gui_button_add(&b_pixytest); //Register Button (and run the callback from now on)
+
+
+
+}
+
+static void leave(void* screen) {
+	gui_button_remove(&b_guitest);
+	gui_button_remove(&b_pixytest);
+}
+
+static void update(void* screen) {
+	//gui_button_redraw(&b_guitest); //only needed if button is overdrawn by others
+}
+
+
+static SCREEN_STRUCT screen = {
+	enter,
+	leave,
+	update
+};
+
+
+SCREEN_STRUCT* get_screen_main() {
+	return &screen;
+}
+
+
diff --git a/common/app/screen_main.h b/common/app/screen_main.h
new file mode 100644
index 0000000..0300b55
--- /dev/null
+++ b/common/app/screen_main.h
@@ -0,0 +1,3 @@
+#include "screen.h"
+
+SCREEN_STRUCT* get_screen_main();
diff --git a/common/app/screen_pixytest.c b/common/app/screen_pixytest.c
new file mode 100644
index 0000000..5f07c69
--- /dev/null
+++ b/common/app/screen_pixytest.c
@@ -0,0 +1,240 @@
+#include "screen_pixytest.h"
+#include "button.h"
+#include "tft.h"
+#include "pixy.h"
+#include <stdlib.h>
+#include "system.h"
+
+static bool pixy_connected = false;
+
+
+static BUTTON_STRUCT b_back;
+
+static void b_back_cb(void* button) {
+        gui_screen_back();
+}
+
+
+static void enter(void* screen) {
+	tft_clear(WHITE);
+	
+	//Back button
+	b_back.base.x1=10; //Start X of Button
+        b_back.base.y1=210; //Start Y of Button
+        b_back.base.x2=AUTO; //b_back.base.x1+160; //Auto Calculate X2 with String Width
+        b_back.base.y2=AUTO; //Auto Calculate Y2 with String Height
+        b_back.txtcolor=WHITE; //Set foreground color
+        b_back.bgcolor=HEX(0xAE1010); //Set background color (Don't take 255 or 0 on at least one channel, to make shadows possible)
+        b_back.font=0; //Select Font
+        b_back.text="Back"; //Set Text (For formatted strings take sprintf)
+        b_back.callback=b_back_cb; //Call b_back_cb as Callback
+        gui_button_add(&b_back); //Register Button (and run the callback from now on)
+
+
+	//Pixy stuff
+        pixy_connected = (pixy_init()==0); //try to connect to pixy
+
+}
+
+static void leave(void* screen) {
+	gui_button_remove(&b_back);
+}
+
+int pixy_led_test();
+int pixy_frame_test();
+
+static void update(void* screen) {
+
+  //Note: The only way to detect that pixy has been disconnected is if a command fails. There's no pixy_is_connected method yet :'(
+
+        if(!pixy_connected) { //Pixy not connected
+                pixy_close(); //Ensure that all pixy resources are freed (failsafe)
+                if(pixy_init()==0) { //try to connect to pixy
+                        pixy_connected=true;
+			printf("pixy reinitialized\n");
+                }
+        }
+
+        if(pixy_connected) {
+                pixy_service(); //Send/receive event data from/to pixy failed
+
+                //Code for tests see below
+                if(pixy_led_test()!=0) {
+                        pixy_connected=false;
+                }
+
+                if(pixy_frame_test()!=0) {
+                         pixy_connected=false;
+                }
+                //system_delay(500);
+        }
+}
+
+
+static SCREEN_STRUCT screen = {
+	enter,
+	leave,
+	update
+};
+
+
+SCREEN_STRUCT* get_screen_pixytest() {
+	return &screen;
+}
+
+
+
+//-----------------------------------------------------------------------------------------------------------------
+
+int colorind;
+const uint32_t colors [] = {0xFF0000, 0x00FF00,0x0000FF,0xFFFF00,0x00FFFF,0xFF00FF,0xFFFFFF,0x000000};
+const int num_colors = sizeof(colors)/sizeof(uint32_t);
+
+int pixy_led_test() {
+        if(colorind==0) {
+                pixy_led_set_max_current(5);
+        }
+
+        int32_t response;
+        int return_value;
+        return_value = pixy_command("led_set", INT32(colors[colorind++]), END_OUT_ARGS,  &response, END_IN_ARGS);
+        colorind%=num_colors;
+
+        if(return_value!=0) {
+                colorind=0; //reset color ind, to start at zero when plugging pixy in again
+        }
+
+        return return_value;
+}
+
+//----------------------------------------------------------------------------------------------------------------------------
+
+int renderBA81(uint8_t renderFlags, uint16_t width, uint16_t height, uint32_t frameLen, uint8_t *frame);
+
+
+int pixy_frame_test() {
+
+ uint8_t* videodata;
+      int32_t response;
+      int32_t fourccc;
+      int8_t renderflags;
+      uint16_t xwidth;
+      uint16_t ywidth;
+      uint32_t size;
+
+
+      int return_value = pixy_command("cam_getFrame",  // String id for remote procedure
+                                      INT8(0x21),     // mode
+                                      INT16(0),        // xoffset
+                                      INT16(0),         // yoffset
+                                      INT16(320),       // width
+                                      INT16(200),       // height
+                                      END_OUT_ARGS,              // separator
+                                      &response,      // pointer to mem address for return value
+                                      &fourccc,
+                                      &renderflags,
+                                      &xwidth,
+                                      &ywidth,
+                                      &size,
+                                      &videodata,        // pointer to mem address for returned frame
+                                      END_IN_ARGS);
+
+      if(return_value==0) {
+            return_value = renderBA81(renderflags,xwidth,ywidth,size,videodata);
+      } 
+      
+      return return_value;
+}   
+
+
+
+
+void interpolateBayer(uint16_t width, uint16_t x, uint16_t y, uint8_t *pixel, uint8_t* r, uint8_t* g, uint8_t* b)
+{
+    if (y&1)
+    {
+        if (x&1)
+        {
+            *r = *pixel;
+            *g = (*(pixel-1)+*(pixel+1)+*(pixel+width)+*(pixel-width))>>2;
+            *b = (*(pixel-width-1)+*(pixel-width+1)+*(pixel+width-1)+*(pixel+width+1))>>2;
+        }
+        else
+        {
+            *r = (*(pixel-1)+*(pixel+1))>>1;
+            *g = *pixel;
+            *b = (*(pixel-width)+*(pixel+width))>>1;
+        }
+    }
+    else
+    {
+        if (x&1)
+        {
+            *r = (*(pixel-width)+*(pixel+width))>>1;
+            *g = *pixel;
+            *b = (*(pixel-1)+*(pixel+1))>>1;
+        }
+        else
+        {
+            *r = (*(pixel-width-1)+*(pixel-width+1)+*(pixel+width-1)+*(pixel+width+1))>>2;
+            *g = (*(pixel-1)+*(pixel+1)+*(pixel+width)+*(pixel-width))>>2;
+            *b = *pixel;
+        }
+    }
+
+}
+
+
+
+
+
+
+int renderBA81(uint8_t renderFlags, uint16_t width, uint16_t height, uint32_t frameLen, uint8_t *frame)
+{   
+    uint16_t x, y;
+    uint8_t r, g, b;
+
+    
+    // skip first line
+    frame += width;
+    
+    // don't render top and bottom rows, and left and rightmost columns because of color
+    // interpolation
+    //uint32_t decodedimage[(width-2)*(height-2)];
+    uint16_t* decodedimage = malloc(sizeof(uint16_t)*(width-2)*(height-2));
+    
+    if(decodedimage==NULL) { //not enough free space to decode image in memory
+        //decode & render image pixel by pixel
+        uint16_t* line = decodedimage;
+        for (y=1; y<height-1; y++)
+        {       
+                frame++;
+                for (x=1; x<width-1; x++, frame++)
+                {   
+                    interpolateBayer(width, x, y, frame, &r, &g, &b);
+                    tft_draw_pixel(x-1,y-1,RGB(r,g,b));
+                }
+                frame++;
+         } 
+    } else { //enough space  
+            uint16_t* line = decodedimage;
+            for (y=1; y<height-1; y++)
+            {   
+                //line = (unsigned int *)img.scanLine(y-1);
+                frame++;
+                for (x=1; x<width-1; x++, frame++)
+                {   
+                    interpolateBayer(width, x, y, frame, &r, &g, &b);
+                    //*line++ = (0xff<<24) | (r<<16) | (g<<8) | (b<<0);
+                    *line++ = RGB(r,g,b);
+                }
+                frame++;
+            }
+            
+            tft_draw_bitmap_unscaled(0,0,width-2,height-2,decodedimage);
+            
+            free(decodedimage);
+    }
+    
+    return 0;
+}
diff --git a/common/app/screen_pixytest.h b/common/app/screen_pixytest.h
new file mode 100644
index 0000000..bcfdfca
--- /dev/null
+++ b/common/app/screen_pixytest.h
@@ -0,0 +1,3 @@
+#include "screen.h"
+
+SCREEN_STRUCT* get_screen_pixytest();
diff --git a/common/gui/button.h b/common/gui/button.h
index 1b347d4..e451943 100644
--- a/common/gui/button.h
+++ b/common/gui/button.h
@@ -1,3 +1,9 @@
+#ifndef BUTTON_H
+#define BUTTON_H
+
+
+#include "touch.h"
+
 
 typedef void (*BUTTON_CALLBACK)(void *button);	//!< Function pointer used...
 typedef struct {
@@ -31,5 +37,8 @@ void gui_button_redraw(BUTTON_STRUCT* button);
 bool guiAddBitmapButton(BITMAPBUTTON_STRUCT* button);
 void guiRemoveBitmapButton(BITMAPBUTTON_STRUCT* button);
 void guiRedrawBitmapButton(BITMAPBUTTON_STRUCT* button);
-
 */
+
+
+
+#endif /* BUTTON_H */
diff --git a/common/gui/screen.c b/common/gui/screen.c
new file mode 100644
index 0000000..23c1498
--- /dev/null
+++ b/common/gui/screen.c
@@ -0,0 +1,58 @@
+#include "screen.h"
+
+
+static SCREEN_STRUCT* screen_list = NULL;
+static SCREEN_STRUCT* screen_current = NULL;
+
+
+SCREEN_STRUCT* gui_screen_get_current() {
+	return screen_current;
+}
+
+void gui_screen_update() {
+	if(screen_current!=NULL) {
+		screen_current->on_update(screen_current);	
+	}
+}
+
+
+
+bool gui_screen_navigate(SCREEN_STRUCT* screen) {
+	if(screen==NULL) return false;
+	screen->next = NULL;
+	if(screen_current!=NULL) {
+		screen_current->on_leave(screen_current);
+		screen_current->next = screen;
+	} else {
+		screen_list=screen;
+	}
+	screen->on_enter(screen);
+	screen_current = screen;	
+	return true;
+}
+
+
+
+bool gui_screen_back() {
+	if(screen_list==NULL) return false;
+	SCREEN_STRUCT* current = screen_list;
+	SCREEN_STRUCT* last = NULL;
+	while(current->next != NULL) {
+		last = current;
+		current = current->next;
+	}
+	if(last==NULL) return false; //There's only a single screen.
+	if(current!=screen_current) return false; //List corrupted?
+	current->on_leave(current);
+	last->next=NULL;
+	last->on_enter(last);
+	screen_current=last;	
+	return true;
+}
+
+
+
+
+
+
+
diff --git a/common/gui/screen.h b/common/gui/screen.h
new file mode 100644
index 0000000..3689007
--- /dev/null
+++ b/common/gui/screen.h
@@ -0,0 +1,25 @@
+#ifndef SCREEN_H
+#define SCREEN_H
+
+
+#include <stdio.h>
+#include <stdbool.h>
+
+typedef void (*SCREEN_CALLBACK)(void* screen);  //!< Function pointer used...
+
+typedef struct SCREEN_S{
+	SCREEN_CALLBACK on_enter;
+	SCREEN_CALLBACK on_leave;
+	SCREEN_CALLBACK on_update;
+
+
+	struct SCREEN_S* next; //Used internally. do not modify
+
+} SCREEN_STRUCT;
+
+bool gui_screen_navigate(SCREEN_STRUCT* screen);
+bool gui_screen_back();
+SCREEN_STRUCT* gui_screen_get_current();
+void gui_screen_update();
+
+#endif /* SCREEN_H */
diff --git a/common/touch/touch.h b/common/touch/touch.h
index 4fd5c25..329538b 100644
--- a/common/touch/touch.h
+++ b/common/touch/touch.h
@@ -1,3 +1,7 @@
+#ifndef TOUCH_H
+#define TOUCH_H
+
+
 #include<stdbool.h>
 #include<stdint.h>
 
@@ -25,3 +29,4 @@ bool touch_register_area(TOUCH_AREA_STRUCT* area);
 void touch_unregister_area(TOUCH_AREA_STRUCT* area);
 
 
+#endif /* TOUCH_H */