[immodule-qt] Some more things for Qt 4

[Lars Knoll]

Hi,

I've got some more comments/questions that came up while we integrated your 
code for Qt 4:

* I don't like the concept of the icHolderWidgets. They require inheriting 
either the widget or QApplication only to specify that a widget should have 
an input context of it's own. I'd prefer a solution where one only needs to 
set a widget attribute to achieve this:
	myWidget->setAttribute(Qt::WA_OwnInputContext);
After this call the widget will have it's own private input context, that one 
can then set/change with QWidget::changeInputContext. IMO this would make the 
usage of private input contexts for certain widgets a lot easier.

* QApplication::changeAllInputContext(), does set all input contexts in the 
app to the new method. I am not sure, but I think that such a method should 
not include input contexts that are private to a certain widget.

* Do we really need one input context per top level widget? Wouldn't it be 
enough to have one per application (apart from private contexts)? We could 
then have QApplication::setInputContext() to change the global (app wide) 
input context, and QWidget::setInputContext() to set a private input context.

* I would like to unify the virtual imStart,imCompose and imEndEvent methods 
into one virtual QWidget::imEvent() method. This will give us more 
flexibility in the future to change and extend the QIMEvent structure.

* The input method needs a way to query properties of the input widget. One 
example is surrounding text, another one is reconversion. The patch I saw for 
surrounding relying on a virtual method to return exatly this one property. 
This has the disadvantage that it is not extensible in the future. For that 
reason I'd like to propose that we add a slightly different virtual method to 
QWidget:
	virtual QVariant imQuery(IMProperty prop);
IMProperty is an enum, that will contain several things:
enum IMProperty {
	IMCursorPosition,
	IMSurroundingText,
	IMCurrentSelection, // for reconversion
	....
};

The advantage of returning a QVariant is that we can put all the information 
we need into this one method, and can freely extend the enum later without 
having to break binary or backwards compatibility.

* imDeleteSurrounding() could then be replaced by a special QIMEvent.

Cheers,
Lars