<Swing Dev> jdk17 on x11: keyboard focus consistently broken on some window managers

[Peter Schuller]

Hello,

I am not certain whether this is the right list to post to since the
problem is likely related to the native integration of the windowing
toolkit rather than Swing itself, but I didn't see a more obviously
correct choice in the list of mailing lists.

The purpose of this post is to find out whether there is a known issue
and whether there is a fix expected for JDK 1.7 release. If not,
whether anyone has ideas or pointers as to what the likely problem is
(I'd like to try to look into it but realistically I will have limited
time to spend on it so any suggestions would be appreciated).

I have been trying to run Swing applications with JDK 1.7 (snapshot
rels or the bsd-port branch in hg depending on platform) for the
massively increased performance (render extension, etc). However I
have consistently seen a keyboard focus problem on several platforms
and window managers and sticking now over some time (i.e., it's not
specific to some particular snapshot release of JDK 1.7).

The manifestation is that keyboard input (for example, trying to enter
text into text fields), has no user-visible effect. The cursor is
lacking text fields, and hitting keys have no effect. This triggers
even on trivial cases like the Notepad JFC demo, as well as larger
apps like IntelliJ. The effect is that it is essentially impossible to
use the keyboard in Swing applications (plain AWT untested), at all
(it is not triggering sporadically, it is happening essentially all
the time as far as I can tell).

I have tried it on the following combinations of OS/window managers:

* succeeds (works): linux x86-64/kde (debian squeeze)
* fails: linux x86-64/stumpwm (debian squeeze)
* fails: freebsd x86-64/icewm
* fails: freebsd x86-64/stumpwm
* fails: freebsd x86-64/xmonad

Now, I know stumpwm/xmonad are not entirely mainstream and the
non-reparenting nature of them has been an issue with Java, but
'icewm' does not feel very obscure to me.

A hint which I didn't mention earlier to try to avoid confusion: In
stumpwm I can actually make keyboard input work by confusing the heck
out of *something*, by doing this:

* Start a virtual desktop with two frames.
* Start a terminal (for example) in one frame, and the Swing
application (e.g. Notepad) in the other.
* At this point keyboard input is broken.
* I hit my stumpwm keyboard combination to switch focus to the *other*
(non-Swing) Window in the other frame.
* I then click the Swing application with my *mouse*.
* I can now enter text in the Swing application ***BUT*** stumpwm is
still convinced that keyboard focus is in the other frame.

I don't know whether that behavior is a stumpwm bug, Java bug, or
something else, but perhaps it may help shed light on what's happening
for someone with more knowledge of the inner workings than me.

I tested to make sure this triggers with an absolutely trivial and
minimalistic JFrame-with-a-JTextField application:

   http://github.com/scode/bug-swingfocus

-- 
/ Peter Schuller