A text edit widget based on QLineEdit.
This widget is extended QLineEdit with custom actions on keypress events - caught and determined usually by the main window then. A new signal CAKeyPressEvent() was introduced for this.
Widget is usually used for editing the lyrics syllables or writing other text in the score. For syllable editing, when left/right cursors are hit at the beginning/end of the line, the next/previous syllable in the score should be selected. This isn't possible to achieve with standard QLineEdit as we need to control KeyPressEvent. This behaviour is again determined in the main window.