[sambarza]

if you set text "sam\n\nhello" in controltextbox its display is:

  sam
  sam
  hello

the problem seems to be in:
xbmc/xbmc/guilib/guitextbox.cpp
method settext (clear of szline is missing):

   // handle the newline character
   if (letter == '\n' )
   {
     cguilistitem item(szline);
     m_vecitems.push_back(item);
     itotallines++;
     ilastspace = -1;
     ilastspaceinline = -1;
     lpos = 0;
     szline[lpos] = 0                       <------- insert
   }

[jmarshall]

:fixed: thanks for reporting it.