I have contacted Dev to find out the complexity of this RFE. Also reassigning it to Mala.

Mala to evaluate the fix which was put together by Vikram Aroskar that works in 6 but not in JDK5. Also contact Yuka for additional consultation.
Windows Vista (Japanese), JRE 1.5.0_17 Swing Application with JTextFields

Text Edit issues were found in IME composition area if caret was moved by
mouse or the mouse selection on composition area.

1. If caret was moved by mouse click while IME composition is active, following
    text input/deletion happens at wrong (at the tail of pre-edit composition area)
    location. If we move caret by arrow keys, following input/deletion happens
    at correct location.

    For example, if text "123456" was typed while composition is
    active and caret was moved to the position between "3" and "4",
    following backspace should delete "3", but it deletes "6".

    If alpha numeric keys were typed, text insertion happens at the end of
    composition pre-edit area, not at the position selected by mouse click.

2. When the text in composition pre-edit area was selected by mouse drag and
    backspace was typed, expected behavior is deleting the selected area,
    but only the last character in the composition area is deleted.

    For example, if text "123456" was typed in and this text was selected by
    mouse drag, following backspace key should remove the text, but only
    "6" at the end is deleted.

These can be easily duplicated with a simple Swing application which has
JTextField with java5 and java6.

Native programs behave as expected in these operations above, i.e. mouse
caret move or selection is reflected correctly in following edit operations.
Is there any progress ?