Text-editors in eclipse/matlab loses focus occasionally after upgrading to 12.04

Question

This is a question asked on stackoverflow, and someone there recommends me to move the question here. My problem is that, I have just upgraded from Ubuntu 10.04 to 12.04.3 LTS. An annoying thing is that, in eclipse and matlab, the text editor loses focus sometimes. The detailed phenomena are as follows:

Eclipse

1. Happens after using auto-completion (activated by customized shortcut alt+/), or switching from other windows, or pressing ctrl+z, etc.
2. Can use mouse to move cursor around, but keyboard does not respond.
3. Using alt-tab to switch back and forth, or click some other parts of the window and click the text field again, can solve the problem.

And similar things are happening in matlab, whenever I hit tab. But gedit and browsers are working fine. I've looked around and tried to disable all kinds of related system shortcuts (such as alt for dashboard popup), and login with gnome classic/ubuntu2d/etc, but none of them solve the problem. Wonder if anyone knows how to get around of it. Thanks.

Answer 1

I've solved the problem and now I understood why this is a problem that only a limited number of people encountered.

So the problem is that I was using SCIM for keyboard input in previous versions of ubuntu, which is out of date and has conflict with many java programs in ubuntu 12.04. As I removed it and switched to iBUS based input method everything works great.

Hope this helps.