QLineEdit::cursorWordForward() don't have the correct behavior on Linux and Mac OS X

The expected behavior of QLineEdit::cursorWordForward() is different depending on the platform. QLineEdit should have a platform specific implementation of QLineEdit::cursorWordForward().

For example, using the text "Qt Software", wordForward is expected to do:
-on Linux: move the cursor between the first 't' and the space
-on Mac OS X: same as on Linux
-on Windows: move the cursor between the space and the 'S'

With the text "Nokia, Qt Software", wordForward is expected to do:
-on Linux: move the cursor between 'a' and ','
-on Mac OS X: same as Linux
-on Windows: move the cursor between the first space and 'Q'
On the three platform, the next wordForward would:
-on Linux: move the cursor between 't' and the second space
-on Mac OS X: same as Linux
-on Windows: move the cursor between the second space and 'S'

The current behavior is not right on any platform.