diff --git a/painter.py b/painter.py
index a532b73..81d35c5 100644
--- a/painter.py
+++ b/painter.py
@@ -23,7 +23,7 @@ class Painter(Widget):
         # list of selected particles
         self.selected=[]
         # complement
-        self.unselected=self.particles
+        self.unselected=[]
 
         # relative position of mouse when moving
         self.offset=Point(0,0)
@@ -250,15 +250,15 @@ class Painter(Widget):
                 return self.adjust_move_element(newdelta,element,recursion_depth+1)
 
 
-    # TODO adapt
     # write configuration to file
     def write(self,file):
         ff=open(file,"w")
         for particle in self.particles:
-            ff.write("{:05.2f},{:05.2f};{:3.1f},{:3.1f},{:3.1f}\n".format(particle.pos.x,particle.pos.y,particle.color[0],particle.color[1],particle.color[2]))
+            if type(particle)==Cross:
+                ff.write("{:d};".format(CROSS_INDEX))
+            ff.write("{:05.2f},{:05.2f};{:3.1f},{:3.1f},{:3.1f}\n".format(particle.squares[0].pos.x,particle.squares[0].pos.y,particle.color[0],particle.color[1],particle.color[2]))
         ff.close()
 
-    # TODO adapt
     # read configuration from file
     def read(self,file):
         self.reset()
@@ -292,40 +292,55 @@ class Painter(Widget):
 
             entries=line.split(";")
             # skip line if improperly formatted
-            if len(entries)>2:
-                print("warning: ignoring line "+str(i)+" in file '"+file+"': more than two ';' spearated entries in '"+line+"'",file=sys.stderr)
+            if len(entries)>3:
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': more than three ';' spearated entries in '"+line+"'",file=sys.stderr)
+            if len(entries)<2:
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': fewer than two ';' spearated entries in '"+line+"'",file=sys.stderr)
                 continue
 
             # position
-            pos_str=entries[0].split(",")
+            pos_str=entries[1].split(",")
             # skip line if improperly formatted
             if len(pos_str)!=2:
-                print("warning: ignoring line "+str(i)+" in file '"+file+"': position '"+entries[0]+"' does not have two components",file=sys.stderr)
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': position '"+entries[1]+"' does not have two components",file=sys.stderr)
                 continue
             try:
                 pos=Point(float(pos_str[0]),float(pos_str[1]))
             except:
-                print("warning: ignoring line "+str(i)+" in file '"+file+"': position '"+entries[0]+"' cannot be read",file=sys.stderr)
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': position '"+entries[1]+"' cannot be read",file=sys.stderr)
                 continue
                 
 
             # color
             color=(0,0,1)
-            if len(entries)==2:
-                color_str=entries[1].split(",")
+            if len(entries)==3:
+                color_str=entries[2].split(",")
                 # skip line if improperly formatted
                 if len(color_str)!=3:
-                    print("warning: ignoring line "+str(i)+" in file '"+file+"': color '"+entries[1]+"' does not have three components",file=sys.stderr)
+                    print("warning: ignoring line "+str(i)+" in file '"+file+"': color '"+entries[2]+"' does not have three components",file=sys.stderr)
                     continue
                 try:
                     color=(float(color_str[0]),float(color_str[1]),float(color_str[2]))
                 except:
-                    print("warning: ignoring line "+str(i)+" in file '"+file+"': color '"+entries[1]+"' cannot be read",file=sys.stderr)
+                    print("warning: ignoring line "+str(i)+" in file '"+file+"': color '"+entries[2]+"' cannot be read",file=sys.stderr)
                     continue
 
-            if self.check_interaction_any(pos,None):
+            # candidate particle
+            try:
+                particle_type=int(entries[0])
+            except:
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': particle type '"+entries[0]+"' is not an integer",file=sys.stderr)
+                continue
+            if particle_type==CROSS_INDEX:
+                candidate=Cross(pos.x,pos.y,color=color)
+            else:
+                print("warning: ignoring line "+str(i)+" in file '"+file+"': unrecognized particle type: '"+entries[0]+"'",file=sys.stderr)
+                continue
+
+            if not self.check_interaction_any(candidate,Point(0,0)):
                 # add to list
-                self.particles.append(Cross(pos.x,pos.y,color=color))
+                self.particles.append(candidate)
+                self.unselected.append(candidate)
             else:
                 print("warning: ignoring line "+str(i)+" in file '"+file+"': particle overlaps with existing particles",file=sys.stderr)
             
@@ -333,3 +348,7 @@ class Painter(Widget):
         self.draw()
 
 
+# global variables (used like precompiler variables)
+CROSS_INDEX=1
+
+