diff --git a/common/gui/screen.c b/common/gui/screen.c
index 1365a5e..8eb3072 100644
--- a/common/gui/screen.c
+++ b/common/gui/screen.c
@@ -6,6 +6,10 @@
  * This makes it safe to change the screen from an touch interrupt (e.g. button callback)
  */
 
+/* Possible Improvements:
+ * Ensure that you can not navigate to a screen which is already in the history (because it will corrupt the list)
+ */
+
 static SCREEN_STRUCT* screen_list = NULL; //Head of the linked list which stores the screen history.
 static SCREEN_STRUCT* screen_current = NULL; //Pointer to the current screen (= tail of the list)
 static volatile SCREEN_STRUCT* screen_goto = NULL; //Screen we should navigate to once we enter the gui_screen_update() method again
diff --git a/common/gui/screen.h b/common/gui/screen.h
index fdef182..8ef82a2 100644
--- a/common/gui/screen.h
+++ b/common/gui/screen.h
@@ -12,7 +12,7 @@
 /**
  * @defgroup screen Screen
  * The Screen Submodule provides an api to navigate between different "screens" on the UI.
- * Each screen must provide an enter, update and a leave method; which will be called from this module at the right time.
+ * Each screen must provide an enter, update and a leave method; which will be called from this module at the right time. 
  * The implemented screens of the application are documented in the \ref screens module.
  */
 /*@}*/
@@ -44,6 +44,7 @@ typedef struct SCREEN_S{
 /**
  * Navigate to the given screen as soon as the app enters the main loop again (and gui_screen_update() is called)
  * It's safe to call this method from an interrupt
+ * @note Do not pass a screen which is already in your history of screens!
  * @param screen A Pointer to the preinitialized SCREEN_STRUCT
  * @return true on success
  */
diff --git a/common/touch/touch.c b/common/touch/touch.c
index 93eac9f..fbd9d5f 100644
--- a/common/touch/touch.c
+++ b/common/touch/touch.c
@@ -12,7 +12,6 @@
 
 /* Possible improvements:
  * Exchange pointer-list "areas" with a linked list. This would ensure that we can always accept new regions
- * Implement calibration stuff, and calculate the real coordinates out of the data provided in touch_add_raw_event()
  */
 
 #define NUM_AREAS 50    //Number of Touch Areas we can manage
diff --git a/doc/docu.odt b/doc/docu.odt
index 8a83070..d7db2d9 100644
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diff --git a/doc/docu.pdf b/doc/docu.pdf
index 9871a38..87c1130 100644
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