[QScintilla] Lexer does not work for me

[wichern]

Hi everyone,

Im using the current 2.6.2 version of QScintilla with Qt 4.8.2 and try 
to get an editor with a C++ lexer:

FcScintillaEditorWidget::FcScintillaEditorWidget(QWidget* a_parent_ptr)
   : QsciScintilla(a_parent_ptr)
{
   QFont l_font;
   l_font.setFamily("Consolas");
   l_font.setFixedPitch(true);
   l_font.setPointSize(10);

   QsciLexerCPP* l_lexer_ptr = new QsciLexerCPP(this);
   l_lexer_ptr->setDefaultFont(l_font);
   this->setLexer(l_lexer_ptr);

   this->setText("// Hello World \n\nint main() { return 0; }");
}

It does display the text with the given lexer font, but there is 
absolutely no colourization.
The complete text is in the QsciLexerCPP::Default colour.

I tried the python lexer too, but with the same result.

What am I doing wrong?

thanks

Paul