The selected text cannot be deleted after applying QLineEdit::backspace () while selected some text in a QLineEdit.

-Preconditions:
1. Qt Creator1.3.0 and Qt 4.6.0
2. The EchoMode of QLineEdit is QLineEdit::Normal
3. A QPushButton to apply method: QLineEdit::backspace ()

-Steps:
1. Input some text in QLineEdit.
2. Select some text in QLineEdit.
3. Press the QPushButton to apply QLineEdit::backspace ()

-Actual result:
The character to the left of the text cursor is deleted but not the selected text.

-Expect result:
According to the description of method: "void QLineEdit::backspace()" in document: "Qt 4.6: QLineEdit Class Reference"
"If no text is selected, deletes the character to the left of the text cursor and moves the cursor one position to the left. If any text is selected, the cursor is moved to the beginning of the selected text and the selected text is deleted."
The selected text should be deleted.