Klaus,
   Ok, on the installer thing. (Please ALSO put "English" on your "Error Codes/messages also", and we could help you more on debugging.)
Found some more "Bugs" on the new screen designer.
1). I have enclosed a screen shot for this one,  When you go to add a New Page lets say 16, it will not let you add the page, and it gives an error, I would tell
you what it was, but it is in your laungauge.
2). I was checking to see if you can look at or edit, "png" style LEDs, when I cliicked on one to look at it, the Screen designer Crashes all together and exits after
clicking on the error dialogs.
3). The vertical sliders appear as a vertical rectangle with a solid color nothing else.
That is far as I got with this Screen designer so far........   I was gonna then Cheack to make sure that the "Dual" state Buttons and "Dual" state LEDs.
Also:  Any luck on adding a "Horizontal" Slider? In the Scream4 source, Art uses standard dc stuff and rectangles, he looks at the screen for the "Slider" Dro format code like this:
if( Format.GetAt(0) == 'S' )
   {
     m_DRO = Format.Find("D") != -1;
     m_Top = Format.Find('T') != -1;
      Slider = true;
      if( Format.Find( "%" ) != -1)
     {
       CString tFormat = Format.Right( format.GetLength() - format.Find("%") );
       format = tFormat;
     }
   }
if( !Slider || (Slider && m_DRO))
      pDC->DrawText( label, size,DT_RIGHT);  //draw the text..
   if( Loaded ) 
   {
      if( !Slider )
        image.image->Draw(pDC);
      else
      {
        image.image->Draw(pDC, tsize ); 
      }
   }
So he pulls the Text that shows it is a slider (I didnt post all the code here), but if it is a slider he formats the rectangle/dc as a vertical slider. I guess you could add an identifier for Horizontal slider and implement the object accordingly.
Scoll Bars:  Can you add scroll bars to the Vertical and Horizontal controls of the Designer Window it self.  For instance if I have a small computer screen, but I want
to design a screen for a larger computer, then I could scroll the designer up or right to get to parts that would not show normally.
scott