diff --git a/common/gui/screen.c b/common/gui/screen.c
index 23c1498..a8a34ea 100644
--- a/common/gui/screen.c
+++ b/common/gui/screen.c
@@ -1,17 +1,36 @@
 #include "screen.h"
 
 
-static SCREEN_STRUCT* screen_list = NULL;
-static SCREEN_STRUCT* screen_current = NULL;
-
+static volatile SCREEN_STRUCT* screen_list = NULL;
+static volatile SCREEN_STRUCT* screen_current = NULL;
+static volatile SCREEN_STRUCT* screen_goto = NULL;
 
 SCREEN_STRUCT* gui_screen_get_current() {
 	return screen_current;
 }
 
 void gui_screen_update() {
-	if(screen_current!=NULL) {
-		screen_current->on_update(screen_current);	
+  	if(screen_goto!=NULL) { //we received the task to switch the screen
+		SCREEN_STRUCT* go = screen_goto; //Backup volatile variable
+		screen_goto=NULL;
+		if(go->next!=NULL) { //we're going back
+		        if(go->next!=screen_current) return; //list corrupted?
+			screen_current->on_leave(screen_current);
+       			go->next=NULL;
+		} else { //we're going forward
+			if(screen_current!=NULL) { //this is not the first screen
+                		screen_current->on_leave(screen_current);
+                		screen_current->next = go;
+        		} else { //first screen ever seen
+                		screen_list=go;
+       			}
+		}
+        	go->on_enter(go);
+       		screen_current = go;
+	}		
+
+	if(screen_current!=NULL) { //A screen has been set
+		screen_current->on_update(screen_current); //Update current screen	
 	}
 }
 
@@ -20,14 +39,7 @@ void gui_screen_update() {
 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;	
+	screen_goto=screen; //send message to main loop, to switch the screen
 	return true;
 }
 
@@ -37,17 +49,15 @@ bool gui_screen_back() {
 	if(screen_list==NULL) return false;
 	SCREEN_STRUCT* current = screen_list;
 	SCREEN_STRUCT* last = NULL;
+	//Find second last element in list
 	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;
+	screen_goto=last; //send message to main loop, to switch the screen
+	return true;	
 }
 
 
diff --git a/common/gui/screen.h b/common/gui/screen.h
index 3689007..375ccbf 100644
--- a/common/gui/screen.h
+++ b/common/gui/screen.h
@@ -17,9 +17,17 @@ typedef struct SCREEN_S{
 
 } SCREEN_STRUCT;
 
+
+//Navigate to the given string as soon as the app enters the main loop again. Method can be called from an interrupt
 bool gui_screen_navigate(SCREEN_STRUCT* screen);
+
+//Navigate one screen back as soon as the app enters the main loop again.  Method can be called from an interrupt
 bool gui_screen_back();
+
+//Returns the current active screen
 SCREEN_STRUCT* gui_screen_get_current();
+
+//Updates/switches the screens. Call this from the app main loop, as fast as you can.
 void gui_screen_update();
 
 #endif /* SCREEN_H */