[Mono-winforms-list] patch for enabling primitive XIM text input

[Doug Rintoul]

I too have been working on a patch for adding XIM support to winforms. I 
had something working last December, but due to a number of factors was 
not ready to submit it for review. However comparing your patch to mine, 
I see we have come up with very similar solutions. There are however a 
couple of problems I found with your patch which can be very easily fixed.

The first problem has to do with the tracking of the control, shift, and 
alt key. These keys will currently get "stuck" because if FosterParent 
filters the key release event, a key release event for these keys are 
never put on the hwnd Queue. For example, if you press CTRL-space to 
enable an IM, winforms still thinks the control key is still pressed, 
even after you release it. Using the left and right cursor keys to move 
around a input field will move a word at a time, rather than a letter at 
a time.

The second issue has to do with the way that IME compose messages are 
handle. A bit of background is required here. I am one of the authors of 
KMFL (kmfl.sourceforge.net), which provides Tavaultesoft Keyman services 
to Linux. The way KMFL is designed is that KMFL can generate multiple 
compose messages in response to a single key stroke. The problem is that 
XIM does not use a FIFO to queue XIM compose messages, but a stack. So 
unless XIM compose events are processed immediately upon receipt, the 
recipient window will receive the XIM compose messages in the reverse 
order that they are generated. The fix is rather easy to implement. We 
just allow the application to process the keypress messages upon receipt 
rather than queuing a whole bunch and then returning. Note that the GTK 
XIM connector and the QT XIM interface work correctly with KMFL, so they 
implement a similar solution.

There is a third issue, the importance of which is debatable. For other 
frameworks (QT, GTK), each window in an application gets its own input 
method, independent of the other windows in an application. For example, 
in a text editor, even though you enable the input method, for the main 
editor, the IM is not enabled for the search box. This may not seem 
important at first, but it can be an issue for multilingual application 
where different fields can have different input methods associated with 
them. The patch I created last November did support this feature; 
however it does add a lot of complexity to the mix.

I am attaching a patch to fix the first two issues. Please considering 
integrating it with your patch if it meets with your approval.

Thanks,


Doug Rintoul
SIL Intl.

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