Using the syntax highlighter example, modified like below.

The will cause the whole document to be re-highlighted the moment the text is edited (input the first character).

This only occur the first time after the file is loaded, pressing more characters is not
causing the file to be re-highlighted.

Change the following class in the example to reproduce:

void MainWindow::setupEditor()
{
QFont font;
font.setFamily("Courier");
font.setFixedPitch(true);
font.setPointSize(10);

editor = new QTextEdit;
editor->setFont(font);

QFile file("mainwindow.h");
if (file.open(QFile::ReadOnly | QFile::Text))

{ QTextDocument *tDoc = new QTextDocument(file.readAll()); highlighter = new Highlighter(tDoc); editor->setDocument(tDoc); }

}