Well, I have never realized that “Arrange Tabs by” menu so far. I checked it some moment ago, “Auto Arrange” is not checked.
I tried to check(tick) it, but the symptom does not go away. So I think “Auto Arrange” has nothing to do with my problem.
Now, I’m back to my office starting a new day, still trying figure out the real reason of this problem. Luckily, I get progress!
Now I have confirmed that the symptom is affected by a software called Kingsoft Powerword Dictionary. The current version is called 谷歌金山词霸 2.0 （Google·Kingsoft Powerword 2.0, gciba 2.0 for short）. Website: http://g.iciba.com . It is the derivation product of the most famous English-Chinese dictionary in China over the past ten years, and now this version is free.
Direct download link(57MB): http://download.iciba.com/pwl/powerwordPE_F.25269.3022.exe
While this gciba 2.0 is running, EmEditor Ctrl+Tab symptom arises(no matter it is v8 or v9). After quitting gciba 2.0, the symptom disappears immediately. This is really hard to imagine.
I have further tested this scenario in a clean WinXP virtual machine, the same result.
I’m sorry to admit that I upgrade my EmEditor from v8 to v9 roughly the same time I upgrade gciba from 1.0 to 2.0, so I had almost concluded that was an EmEditor issue.
So, Yukata, if you have time, could you install gciba 2.0(all use default) and debug your code to see why this happens?