Regression: Wrong text cursor movement when running on Qt 4.8.1

1. Build Creator from current 2.5 branch on Qt 4.8.0.
2. Run the resulting Creator on Qt 4.8.0.
3. Open a text file.
4. Select everything in this file by pressing Ctrl+A.
5. Press the Left Arrow key.
   The selection will be cleared and the cursor will be right before the last character of the file.
   This is standard behavior in most programs.

Now do the same with the same Creator running on Qt 4.8.1.
In step 5, the cursor will be moved to the very beginning of the file. This is non-native behavior and therefore a bug.

Found by Squish test suite_general/tst_select_all