No generic way to limit input method modes

Qt provides InputMethodHints and/or InputMethodQuery for controlling Input Method behaviour. However, these are not good enough for specific input method especially Japanese input method for mobile phones.

For example, Japanese phonebook entry has a "reading" or "pronunciation" field to sort entries as a Kanji character has usually various ways to pronounce and sorting by Kanji character codes is not useful for users. In the field, end-user would expect that the input method modes are limited to half-width Katakana, Alphabet or number mode excluding full width and Hiragana-Kanji conversion modes.

InputMethodHints is not suitable for the case as it consists of exclusive flags that cannot specify several suitable input method modes. On the other hand, InputMethodQuery would be suitable for the case but currently no constant is defined to ask input-method-enabled text editor about suitable input method modes. Please note that filtering is not suitable way for the case as this is a story about input method modes, not composing or committing string.

If Qt::InputMethodQuery has a new constant like ImSuitableModes or ImSuitableScripts and it returns an QVariant of QList<QVariant> where the list contains an QVariant for an Unicode script, http://www.unicode.org/charts/#scripts. Say, Halfwidth Katakana, ASCII Characters and ASCII Digits would be specified for the reading (or pronunciation) field in Japanese phonebook entry. This way is very similar to java.awt.im.InputContext#setCharacterSubsets in Java Input Method Framework. See http://java.sun.com/javase/6/docs/api/java/awt/im/InputContext.html#setCharacterSubsets%28java.lang.Character.Subset[]%29 for detail.

In addition, if QWidget and QGrahicsItem have properties to return these Unicode substs, it would be much nicer for developers to support applications for Japanese language.

Please note that most of Japanese mobile phone uses would feel comfortable if input method mode will be changed according to focused text editor implicitly. Otherwise, they would get frustrated to change its mode explicitly. Say, alpha numeric modes for URL, Kana-kanji conversion and alnum modes for notepad. This is very important feature. I would expect Qt Input Method Framework would support this not only for Japanese market but also open for other non-Latin languages.