Status: Unconfirmed
Owner: ----
Labels: OS-Linux Area-Misc Size-Medium Type-Bug

New issue 17001 by mathrick: Regression: IME contexts mismanaged between  
tabs and omnibox
http://code.google.com/p/chromium/issues/detail?id=17001

Chrome Version  : Chromium r20583
OS + version    : Ubuntu Linux 9.04
CPU architecture: x86-32
window manager  : Metacity

In chromium GTK+ builds r2583 and above, a regression has crept in in how
input method contexts are managed between the omnibox and tabs' content
areas. This issue is only visible when using a non-trivial IME, the default
gtk-im-context-simple does *not* expose it.

What steps will reproduce the problem?
1. Make sure a sufficiently complex IME is installed. SCIM or UIM with
Japanese input enabled are good.
2. For best result, make sure the IME shows some kind of indication of what
mode it is in, such as SCIM's toolbar. UIM with "show input mode nearby
cursor" enabled works best, as it shows exactly which window triggered the
IME change. A compositing WM with drop-shadows enabled will also let you
estimate visually the number of changes that happen.
3. Run chromium from the commandline as GTK_IM_MODULE=uim ./chrome. This
forces uim to be the default IME. Verify it worked by right-clicking on the
omnibox and checking if in "Input methods" submenu "System (uim)" is
selected.
4. Open a chromium window with 20+ tabs. The contents don't matter, they
can be empty.
5. In the last tab navigate to an URL, so that there's something to select
in the omnibox.
6. Try double-clicking to select the URL in omnibox. Then try clicking on
the content area and omnibox again. Notice the time it took to complete and
the CPU usage.

What is the expected result?
Nothing special happens. The current IME context switches away from the tab
and into the omnibox, as indicated by the UIM input mode popup. The process
is immediate.

What happens instead?
The popup appears over the omnibox, then several times (3?) back over the
tab content area. This happens for every click, and *every tab open in the
window*. This means that with 20+ tabs, double-clicking on the URL might
take 5s-10s to complete, during which the popups stack (as evidenced by the
very dark composited drop-shadow) before they're dismissed. The CPU usage
is at 100%.

Please provide any additional information below.
I have tracked it down to a change between r20568 and r20583. r20568 works
fine, r20583 shows the regressed behaviour. Unfortunately I can't narrow it
down any further, as there are no builds available in between, and I can't
afford setting up a chromium build env.

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