diff --git a/src/engine.c b/src/engine.c
index afb09258..38fee55d 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -1599,11 +1599,20 @@ void Main_handler(void)
 
 //----------------------- Tracer une fenêtre d'options -----------------------
 
-void Open_window(word width,word height, const char * title)
-// Lors de l'appel à cette procédure, la souris doit être affichée.
-// En sortie de cette procedure, la souris est effacée.
+/**
+ * Open a GUI window
+ *
+ * @param width window width
+ * @param height window height
+ * @param title window title
+ *
+ * The mouse must be shown before calling this function. The mouse is hidden
+ * when the function returns.
+ *
+ * The function Close_window() must be called afterward.
+ */
+void Open_window(word width, word height, const char * title)
 {
-  //word i,j;
   size_t title_length;
 
   Hide_cursor();
@@ -1620,6 +1629,12 @@ void Open_window(word width,word height, const char * title)
     
   Windows_open++;
 
+  // Limit the window size to the screen size
+  if (width > Screen_width)
+    width = Screen_width;
+  if (height > Screen_height)
+    height = Screen_height;
+
   Window_width=width;
   Window_height=height;
 
@@ -1627,6 +1642,8 @@ void Open_window(word width,word height, const char * title)
   Window_pos_X=(Screen_width-(width*Menu_factor_X))>>1;
 
   Window_pos_Y=(Screen_height-(height*Menu_factor_Y))>>1;
+
+  GFX2_Log(GFX2_DEBUG, "Open_window(%d, %d, \"%s\") pos (%d,%d)\n", width, height, title, Window_pos_X, Window_pos_Y);
   
   Window_draggable=1;
 
@@ -1682,9 +1699,13 @@ void Open_window(word width,word height, const char * title)
 
 //----------------------- Fermer une fenêtre d'options -----------------------
 
+/**
+ * Close a window previously open with Open_window()
+ *
+ * The mouse must be shown when this functions is called.
+ * It is hidden when the function returns.
+ */
 void Close_window(void)
-// Lors de l'appel à cette procedure, la souris doit être affichée.
-// En sortie de cette procedure, la souris est effacée.
 {
   T_Normal_button   * temp1;
   T_Palette_button  * temp2;